Newton's law of motion Questions and Answers

7 During a snowball fight a 0 35 kilogram snowball traveling at a speed of 18 0 m s hits a student in the back of the head If the contact time is 0 13 s what is the magnitude of the average force on the student s head

Determine the reactions at the roller A and the pin C 6 kN 6 kN E 3 m 4 3 m B D 8 kN 3 m C

23 A stone is thrown straight up At the top of its path the net force acting on it is equal to its weight greater than its weight 24 Is it possible for an object moving with a constant speed to accelerate Explain a Yes although the speed is constant the object s direction can be changing Yes if an object is moving it can experience acceleration b No an object can accelerate only if there is a net force acting on it d No if the speed is constant then the acceleration is equal to zero C a b C zero d greater than zero but less than its weight a 25 When a car drives around a traffic circle at constant speed c d The car is accelerating toward the center of the traffic circle The car is accelerating away from the center of the circle The car is accelerating forward The car is not accelerating 26 A 65 kg person is riding on a Ferris Wheel with a radius of 9 3 m As the wheel turns the speed of the rider is 4 8 m s What is the rider s acceleration 2 5 m s b 58 m s c 4 5 m s 27 A net force F accelerates a mass m with an acceleration a If the same net force is applied to an object with twice the mass then the acceleration will be half as much b twice as much c four times as much d one fourth as much c 8 0 kg FARB 28 When a person is on a circular motion ride like turkish twist what causes the person to move in a circle a There is no force it s the inertia of the person 6 The force of friction between the person and the wall of the ride C TH ormal force from the wall of the ride d The weight of the rider 30 When an object is moving at a constant velocity a the forces on the object are unbalanced b the net force is equal to the velocity WAS d 6 6 m s 29 An object sits on a frictionless surface A 12 N horizontal force is applied to the object and it accelerates at 3 0 m s What is the mass of the object a 4 0 kg b 32 kg c the net force equals zero d only one force acts on the object d 78 N

9 An acorn falls from a tree As it falls compare its kinetic energy E to its potential energy E a E increases and E increases b Ex increases and decreases C Ex decreases and decreases d E decreases and E increases C 10 A person is standing on a bathroom scale while riding in an elevator The elevator is moving up at consta speed What is the value of the normal force on the person d greater than mg a b exactly mg C less than mg d cannot be determined without knowing the speed 11 Consider two masses m and m at the top of two frictionless inclined planes Both masses start from rest at the same height However the plane on which m1 sits is at an angle of 30 with the horizontal while the plane on which m2 sits is at 60 If the masses are released which is going faster at the bottom of its plane a m1 b m2 c They both are going the same speed d cannot be determined without knowing the masses 12 If no outside net force acts on a moving object EF 0 the moving object will a stop immediately b move with constant velocity C go faster and faster d slow down and eventually come to a stop 3 Compared to its mass on the Earth the mass of an object on the Moon is a the same b more M C half as much d less 30 A person with a weight of 700 N stands on a bathroom scale that is on an inclined ramp If the s Hewtons it will show a 700 N b ON more than 700 N less than 700 M

A box is sliding down a slope that makes an angle of 35 0 to the horizontal If the mass of the box is 15 0kg what is the parallel component of the weight 8 60N 12 3N 120 N 84 3N

1 The measure of the gravitational attraction between an object and the earth is defined as a weight b mass Newton d Normal force 2 A ball is tossed upward into the air Ignore air resistance What direction is the net force on the ball when it is in the air Upward b Downward c first upward then downward d first downward then upward 3 A book sits at rest on a table The table puts a force upward on the book According to Newton s Third Law a The earth puts an equal force downward on the book The earth puts an equal force upward on the table C The book puts an equal force downward on the table d The table puts an equal force downward on the earth 4 A bowling ball is raised a height above the surface of the earth and the separation of the ball and the earth stores 10 J of gravitational potential energy If an identical bowling ball is raised three times as high the amount of energy stored in the separation is a 30J 60 J c 90 J d 120 J 5 If a golf club applies a 2400 N force to a golf ball the ball applies 2400 N force to the club in the same direction b 2400 N force to the club in the opposite direction C a force less than 2400 N due to the lower mass of the ball d a force greater than 2400 N due to the higher mass of the club A particular spring stretches 2 5 cm when a mass of 200 g hangs on it If the 200 g mass is replaced with a 600 g mass the spring will stretch a 5 0 cm b 6 25 cm c 7 5 cm d 10 cm A block of mass M slides down a frictionless plane inclined at an angle 8 with the horizontal The gravitational force is directed toward the center of the Earth b perpendicular to the plane c parallel to the plane in the same direction as the movement of the block d parallel to the plane in the opposite direction as the movement of the block A box sitting on a horizontal surface is pulled by a 5 0 N horizontal force A 3 0 N friction force acts on the ox What is the net force acting on the object a ON b 2 N 5N d 8 N

15 An object sits on a frictionless surface A 16 N horizontal force is applied to 2 0 m s What is the mass of the object a 8 0 kg b 78 N c 4 0 kg d 32 kg 16 You are standing in a moving bus facing forward and you suddenly fall toward the front of the bus You can imply from this that the bus s a velocity decreased b velocity increased C d speed remained the same but it s turning to the left speed remained the same but it s turning to the right 17 A ball falls from the top of a building through the air to the ground below Air resistance acts on the bellet falls How does the kinetic energy E just before striking the ground compare to the gravitational energy E at the top of the building a b E is equal to E E is less than E E is greater than E d It is impossible to tell 18 A person is standing on a scale in an elevator accelerating downward Compare the reading on the scale to the person s true weight a greater than their true weight b less than their true weight c equal to their true weight d zero 19 A 1 2 kg ball of clay is released from a height of 1 3 m above the ground How much thermal energy is generated when it hits the ground and comes to a stop a OJ b 1 6 J C 4 8 J 20 A constant net force acts on an object Describe the motion of the object a constant speed b increasing acceleration C constant acceleration d constant velocity 21 According to Newton s 2nd Law the acceleration of an object is directly proportional to a its velocity b its mass its position the net force acting on it 22 A 90 kg object has a weight of a 882 N d 15 J b 9 18 c 90 N d 99 8 N

3 In the pulley system shown all the pulleys are massless and frictionless and the rope is of negligible mass The block has a weight of 2500 newtons a Find the tension in the rope if the block is lifted at a constant velocity b Find the mechanical advantage of the pulley system 2500 N

incline of incline angle and attached to an initially relaxed nonlinear spring which exerts a restoring force of magnitude fres x kx ax Here x is measured parallel to the incline from the block s initial position where the spring is relaxed The coefficient of kinetic friction is itself position dependent and is given by Mk x Mo 1 x L i e the the incline gets smoother as the block descends Leave g symbolically x L Find the block s speed as a function of x assuming that it does start moving down the incline and for the first phase of motion during which it is moving down the incline given that it starts from rest at x 0

Determine the tension in wire AB C is a pin connection 30 3 ft 4 ft 2 5 kip

1 point The normal would be equal to the weight a box sitting on the floor a box being pushed by a horizontal force so it accelerates across the floor on an elevator traveling upward at a constant velocity in all of these cases the normal is equal to the weight

A 6 0 kg bucket of water is raised from a well by a rope If the upward acceleration of the bucket is 3 6 m s2 find the force exerted by the rope on the bucket N

Consider the figure below a Find the tension in each cable supporting the 696 N cat burglar Assume the angle of the inclined cable is 38 0 inclined cable N horizontal cable vertical cable N b Suppose the horizontal cable were reattached higher up on the wall Would the tension in the inclined cable increase decrease or stay the sa O increase decrease stay the same

speed It is used to transport people from one location to another within a large building such as an airport The diagram shows a moving walkway The table shows data about two people on the same moving walkway Person 1 steps onto the walkway from rest and stands on it Person 2 steps onto the walkway while already walking and continues to walk a Using the data for person 1 calculate the speed of the walkway Show your calculations and include units in your answer Stepping onto the walkway person 1 accelerates from an initial speed of 0 m s to the speed of the walkway in 0 6 s b Calculate the acceleration of person 1 Show your calculations and include units in your answer c Calculate the net force that accelerated person 1 Show your calculations and include units in your answer Person 1 and person 2 have the same acceleration as they step onto the moving walkway d Identify whether the net force acting on person 1 is greater than less than or equal to the net force acting on person 2 Explain your answer Person Mass kg 88 Direction of motion Moving walkway Distance Moved on Walkway m 120 Time on Walkway s 240 4 pc

Find the forces T and T2 I T1 T2 The second box is for the units 37 T 67 49 lb T 0 1 pt 398 Details

2 A box slides down an inclined plane with an acceleration that is precisely three fifths what it would have been if the slide had been frictionless Calculate the angle of the incline if the coefficient of kinetic friction of the rough incline is 0 28 a 3 5 of FN mg c FK angle of in cline p 28 Fparallel coordinate Mmas

22 A rocket engine thrusts the rocket into space because O the exhaust pushes against the ground every action produces an equal and opposite reaction matter and energy are conserved 23 A student pushes against a wall with 20 N of force and the wall does 3 poin not move In this situation the wall exerts 20 N 2 0 N 0 20 N 3 poll OON

Two elephants are pushing on a log from two sides One elephant pushes with a force of 1000N to the right and the force of 950N to the left the other elephant pusher with OL mass of the log is 150kg The log started at rest what is the Velocity of the logafter 1 seconds

20 An object in motion with no unbalanced force acting on it will O eventually slow down and come to a complete stop Oslow down but never quite stop O continue to move in its path at constant speed accelerate and eventually reach the speed of light 21 If F1 is greater than F2 then the box is 3 points M FRICTIONLESS TABLE 3 points In the diagram below box M is on a frictionless table with forces F and F2 acting as shown F2 F

24 As shown in the diagram below an inflated balloon released from rest moves horizontally with velocity v The law that best explains this event is Newton s 1st Law O Newton s 2nd Law Newton s 3rd Law Air Balloon 25 What does the astronaut observe Note The Moon has no atmosphere 3 points 3 points

5 A 40 N force acting 60 and a 40 N force acting 120 act concurrently at a point What is the magnitude and direction of the resultant What is the magnitude and direction of a third force that produces equilibrium at the point

Question 20 Use excel to find the resultant of the forces shown in Fig 6 below 40kN 70kN 210 50 20 120 Fig 10 120kN 100kN

In 1865 Jules Verne proposed sending men to the Moon by firing a space capsule from a 220 m long cannon with final speed of 10 97 km s What would have been the unrealistically large acceleration experienced by the space travelers during their launch A human can stand an acceleration of 15g for a short time m s Compare your answer with the free fall acceleration 9 80 m s i e how many times stronger than gravity is this force g

Two people hang motionless from a vertically hanging rope The person closer to the top has a mass of 80 0 kg the person below him has a mass of 50 0 kg and the mass of the rope is negligible Part 1

5 A m 5 00 kg block on a smooth tabletop is attached by a string to a hanging block of mass m 2 70 kg as shown in the figure The blocks are released from rest and allowed to move freely Find the tension in the string 17 1818 On First Attempt 1 17 2 N TIL

Calculate the force a pogo stick must exert on the ground to produce an upward acceleration 4 00 times the acceleration due to gravity Assume the mass of the pogo stick plus its rider is 66 5 kg

3 The system shown in the following figure is in static equilibrium Given that the mass m is 8 80 kg and the coefficient of static friction between mass m and the surface on which it rests is 0 34 what is the maximum mass that m can have for which the system will still remain in equilibrium kg

5 A large box is pulled by a person with a force as shown in the figure The angle 8 26 What is the magnitude of the normal force at the moment when the box is about to move if the mass of the box is m 27 0 kg and the coefficient of static friction between the box and the floor is 0 63 N

4 Two blocks are connected by a string as shown in the figure The smooth inclined surface makes an angle of 9 43 with the horizontal and the block on the incline has a mass m 7 5 kg Find the mass m of the hanging block that will cause the system to be in equilibrium D

1 Two lifeguards pull on ropes attached to a raft If they pull in the same direction the raft experiences a net force of 334 N to the right If they pull in opposite directions the raft experiences a net force of 106 N to the left a Draw a free body diagram representing the raft for each situation b Find the force exerted by each lifeguard on the raft for each situation Disregard any other forces acting on the raft

Each answer in this assignment is worth a maximum of one point 1 How much tension must a rope withstand if it is used to accelerate a 1900 kg car vertically upward at 0 70 m s

Find the shear and moment equations for the beam loaded as shown if P 463 lb W 231 lb ft a 6 7 ft and b 14 5 ft Then Find the SHEAR FORCE 9 39 ft to the right of B Round off the final answer in lb to two decimal places P B W C

1 Four blocks with masses m 5 90 kg m 5 20 kg m3 7 70 kg and m4 7 80 kg are pulled on a horizontal frictionless surface by a 32 0 N force that makes a 25 angle 0 with the horizontal see figure What is the magnitude of the tension between the m3 and m4 blocks N

Fe k 72 k 9x10 E K2 F Eq RT R R R3 F qvB V IR ni sin 0 n sin 0 B 1 Po 2 r Ho 1 1 1 RT R 1 R R3 4 x10 7 1 Mr Mangan drops a pumpkin from the top of a building It takes 2 5 seconds for the pumpkin to hit the ground How tall is the building V V tat 2 Mr Mangan is pushing a 90 kg box with a force of 350 N If there is a coefficient of kinetic friction of 0 3 between the box and the floor what is the acceleration of the

Question 13 A box hangs from a string that runs over a pulley and back to where a second box hangs Select all the following that apply A weight mg pulling straight down on both boxes B the normal force pushing straight up on both boxes C the string pulling to the right D friction resisting the motion pulling to the left E the tension in the string pulling straight up on both boxes F the tension in the string pulling straight up only on the heavier box

A man stops the fall of a block on the ground by applying a force against a vertical wall as shown in figure If weight of block is 5 kg and coefficient of static friction is 0 5 then the minimum force applied by him will be 5 kg F Wall 250 N 500 N 100 N

In the shown arrangement pulley is smooth and string is ideal If system is set free to move then answer the following questions A O 15 Minimum value of coefficient of friction min so that block A has zero acceleration in vertical direction is 2 3 4 LL m A 16 If u 1 then acceleration of block A will be A 5 C 3 7 smooth B B D 312 314 4 m 3

A block of mass 1 kg is resting over a rough inclined plane and a force F of magnitude 2 N is applied vertically upward as shown in figure then magnitude of net contact force in N on the block by the inclined plane will be F 2N Rough surface 37 1 kg

Two rods AC and BC are hinged at the end C and the ends A and B are moving along the surface with velocities v 8 m s and v 4 3 m s respectively as shown VA VB The velocity of hinged point C is A 13 m s v 8m s B 2 13 m s 60 30 B V 4 3m s C 3 13 m s D 4 13 m s

A Diwali rocket is fired from ground at time t 0 and it goes straight up Take the launch point as origin and vertically upward direction as positive y direction The acceleration of the rocket is given by a g kt 0 t to g t 3g V k to where to A Maximum velocity of the rocket during 2g g k the up journey is 3 Maximum height attained by the rocket is B 3g 4k Maximum height attained by the rocket is C 3g 8k The D 3g time of flight of rocket is 1 1

A car is moving with 5m s accelera horizontally as shown There is no frictio any contact surface The reading of a 1 spring balance in N at the instant show Take g 10 m s Assume the hanging pa string is vertical 10kg Spring Balance 000000 37 a 5m s 10kg

27 The diagrams show two ways of hanging the same In both cases a string is attached to the same points on the picture and looped symmetrically over a nail in a wall The forces shown are those that act on the nail In diagram 1 the string loop is shorter than in diagram 2 Which information about the magnitude of the forces is correct nail diagram 1 R R T T R R T T nail T R T diagram 2 2 R R T T 4 R R T T picture fr af for 2 3778 CH Udic nh R I HII Shi nail T R TWSOT TIOL who whor R diagram 1 1 R R T T 3 R R I T wol nail T R T diagram 2 2 R R T T A R D 1 22 m 2 15 m 3 29 m 4 28 m The greatest have is a Th from one s 1 2 2d

Three blocks A B and C of masses 4 kg 2 kg and 1 kg respectively are in contact on a frictionless surface as shown If a force of 14 N is applied on the 4 kg block then the contact force between A and Bis 18 N 2 N 06 N 8 N B la

An open container filled with a liquid is revolved in a vertical circle of radius 2 5 m with constant speed The maximum time period of revolution so that liquid does not spill out will be 2 s 3 14 s 4 21 S

Two monkeys A B of same mass m 1kg are hanging on the strings such that block of mass 2 kg remains at rest and it is given that monkey B is just holding the string Then which of the following statement s are CORRECT g 10 m s A m A B C D 2kg B Acceleration of monkey B is 10 m s upwards Acceleration of monkey A is 30 m s upwards Acceleration of monkey A with respect to his rope is 35 m s upwards Acceleration of monkey B with respect to his rope is 50 m s upwards

Find acceleration of block in given figure 1 6 m s2 2 11 m s 10kg 37 50 N 28 08 1021 NERT GRAND TEST 3 1 m s

A uniform chain of length is released from rest on a smooth horizontal table with a portion h of the chain overhanging as shown in the figure Find the time taken by the chain to slip off the table

Q 93 In following arrangement the coefficient of Q 93 friction between all the surfaces in contact is 0 4 It is given that m 3 kg and m 5 kg Find the maximum value of F for which the slipping occurs at one surface only 1 40 N 3 64 N m m 2 32 N 4 44 N 0 481 1 40 N 3 64 N m 5 kg furra for forens ffm 3 kg for m m 2 32 N 4 44 N a TI

Two blocks A and B of masses 2 m and m respectively are connected by a massless inextensible string The whole system is suspended by a massless spring as shown in figure The magnitude of acceleration of A and B immediately after the string is cut are respectively Ma T Ma Jonag 1 T Rm Mag 2 T Mg Ma Mg M X 9 2 3 g g jeeeee T Mg Ma g 2 nags T Rn Mg Mg T Mg Mg 1 T Mg Mo Mo 2 2 9 4 29 g

A balloon was moving upwards with a uniform velocity of 10 m s An object of finite mass is dropped from Fongo the balloon when it was at a height of 75 m from the ground level The height of the balloon from the ground when object strikes the ground was around takes the value of g as 10 m s 1 300 mongo 2 200 m 3 125 m 4 250 miongo mathongo mathongo mathongo mathongo mathongo mathongo mathongo mathongo mathongo mathongo mathongo mathongo mothongo mathongo mathongo mathonge mathongo mathonco mo mathoncomathongo mathongo