Work, power & energy Questions and Answers

The following situation may or may not be consistent with the principle of conservation of mechanical energy For the following example state whether mechanical energy is conserved or not conserved Only choose one of the above answers and type the answer exactly as written above An obiect moves up hill with a decreasing speed

A smooth 0 16 kg hockey puck slides across a smooth gym floor and experiences a frictional force of 0 36 N and stops in a distance of 2 3 m Calculate the work done by the normal force that the floor exerts upward on the puck

A student pulls a wagon full of textbooks 25 0 m with a force of 32 0 N at an angle of 30 to the horizontal Her work done on the wagon full of books is

ype the correct answer in each box eff is part of a trekking team As he climbs a hill he drops his water bottle which has a mass of 0 25 kilograms The bottle slides down the hill and is moving at a velocity of 14 meters second the instant it hits the ground The vertical height fr KE mv PE mxgx h and g 9 8 m s dropped the bottle is meters Ignore friction and use Reset Next

object another 5m what is the object s new kinetic energy An object has 65J of kinetic energy If a 15N force pushes the already moving

10 0 045 X 0 212 x Which path going up the mountain will have more potential energy Path A which is less steep but takes longer Path B which is steep but less distance Path A Path B

A suitcase is pushed along a ramp from 2 0 to 6 0 with a 65 N force at 60 to the ramp Distances on the ramp are measured in metres How much mechanical work is done

20 A 19 kg box of math books is carried up a set of stairs that is 8 m long and inclined at 50 How much work is done against gravity 21 A rock climber pulls himself 21 m up the side of a cliff with a force of 5 2 N at an angle of 11 2 to the vertical What is the work done 22 A storage box is dragged 7 m along a smooth level floor by a 43 N force applied at 38 to the floor Then it is pulled 3 5 m up a ramp inclined at 24 to the horizontal using the same force The storage box is then dragged a further 6 m along a level platform using the same force again Determine the total work done in moving the storage box

Sa If a 5kg object has potential energy before it is dropped from a 200m building how much kinetic energy will it have before hitting the ground Sb hitting the ground Using the information above what is the object s velocity before

2 You and an elephant are having a sled race down the hill next to the school You both start at the same height a Who has more potential energy b Who reaches the bottom of the hill first c Who is going the fastest at the bottom of the hill d Who has more kinetic energy at the bottom of the hill

A roller coaster car of mass 1500 kg starts from rest at an elevation of 35 0 m high and rolls down and then up another incline of lower height 18 0 m a How much potential energy does the roller coaster have at the starting position b How much kinetic energy does the roller coaster have at the starting position c Find the total energy of the roller coaster d How much potential energy does the coaster have at the lower elevation e How much kinetic energy does the coaster have at the lower elevation 0 How fast is the coaster traveling

com lifts Jerry weighing 1 2 N into the air so that he can reach a countertop 1 3 m above him How much work does Tom do

A 0 321 kg ball is moving upward with a speed of 32 5 m s when at a height of 17 4 meters above the ground Determine the total mechanical energy of the ball

In a physics lab a 54 kg student runs up a 2 2 meter tall flight of stairs in 4 9 seconds Find the student s power rating

Determine the amount of work done by an upward force is applied to lift a 1 9 kg object to a height of 7 5 meters at constant speed Remember you need the gravitational force

A sledder effortlessly glides from position A across the snow to position B as shown in the diagram below Position A KE 4000J PE 8000J Resistance forces are negligible At position B the kinetic energy of the sledder is position A to position B the sledder lost Position B KE PE 5000 J Joules and the total mechanical energy is Joules of potential energy and gained Joules In moving from Joules of kinetic energy

5 Newton force is applied to a 2 kg object to move it across a horizontal surface at a constant speed for a distance of 4 meters The free body diagram is shown below Which of the following forces are doing work upon the object either positive or negative Ffrict c Normal force Fnorm Egrav List all that apply in alphabetical order with no commas or spaces between letters a Applied force b Friction force d Gravity force e nonsense None of these forces are doing work Fapp

Calculate the kinetic energy of a 0 6 kg object moving at 4 71 m s

5 What is the energy required to power a 1000 Watt microwave for 2 minutes 10 points

Let F 4xe i 2x e Let C be the path consisting of line from 0 0 to 8 0 to 8 2 to 0 0 find F di C

57 5 kg cross country skier uses her poles to accelerate from rest to a speed of 8 75 m s in 29 9 seconds Determine the power generated by the jer

Ou push a wheelbarrow a distance of 58 5 m at a constant speed for 29 9 s by exerting a 198 N force horizontally What power do you develop

Determine the total mechanical energy of a 58 5 kg skier when he s at a height of 21 6 m and moving at 25 8 m

3 force 41 j 3k N Find the work done F K xi yj is working on a particle which moves from 0 0 to a 0 along x axis and a 0 to a a along y axis Find the work done by the force

0 YOU WILL HAVE CERTAIN AMOUNT OF TIME AND DAYS AND ONE ATTEMPT TO SUMMIT YOUR TE ONCE YOU OPEN THE TEST OR QUIZ TIME STARTS COUNTING ALL CALCULATIONS MUST BE WRITTEN IN THE SAME ORDER OF YOUR TEST AFTER COMPLETING THE TEST OR QUIZ TO YOU MUST UPLOAD ONE DOCUMENT WITH ALL YOU OF TIME TO UPLOAD YOUR CALCULATIONS I WILL NOT ACCEPT LATE CALCULATIONS OR IF YOU SEND IT TO MY EMAIL FAILURE TO DO SO WILL GRANT YOU A ZERO FOR EVERY QUESTION THAT REQUIRES A CALCULA IF YOU ENCOUNTER ISSUES WITH YOUR INTERNET CONNECTION DURING THE TEST CONTACT M RESOLUTION IF YOU WAIT UNTIL LAST MINUTE TO COMPLETE YOUR TEST THE ABOVE WILL NOT Question 1

A 70 0 kg skier starting from rest at A travels down a hill shown in the figure below If H 100 0 m What is the kinetic energy in Joules of the skater at point B Neglect friction Use g 9 80 m s Your Answer H Potential Energy 0

Particle A and particle B each of mass M move along the x axis exerting a force on each other The potential energy of the system of two particles associated with the force is given by the equation U B r where r is the distance between the two particles and is a positive constant At time t 0 particle A is located at x 2D with an initial speed of vo to the left and particle B is at rest at the origin as shown in the figure above 9 At time t T particle A is observed to be traveling with speed 2v0 3 to the left The speed and direction of motion of particle B is A 2v0 3 to the left B vo 3 to the left C vo 3 to the right D 2v0 3 to the right E 5vo 3 to the right 10 Which of the following equations could be used to find MIN the minimum distance between the masses as particle A approaches particle B B A 4D B 4D B C B Mv M MIN D B 4D B 4D Mv Mv B MIN B 2 MIN B 2 PAN M Vo 2 1 2 2

5 When should you apply the conservation of momentum equation

bottom end measured vertically a What is her gravitational potential energy at the top of the slide relative to the bottom 1 2 kJ b What is her kinetic energy when she reaches the bottom 94 J c How much energy is lost due to friction 1 1 kJ d Calculate the average frictional force acting on her as she goes down the slide 110 N

5 In the diagram below 400 joules of work is done raising a 72 newton weight a vertical distance of 5 0 meters lo bosges s 5 0 m 72 N 72 N Pulley Force How much work is done to overcome friction as the weight is raised A 40 J B 360 J

24 A ball vibrates back and forth from of 20 N m If the amplitude of this

Question 4 e Round your answer to 2 decimal places C VST 10 Points Two masses collide on a frictionless horizontal floor and in a perfectly inelastic collision Mass 1 is 4 times that of mass 2 Velocity of mass 1 12 m s to the right while the velocity of mass 2 18 m s to the left What is the velocity and direction of the resulting combined mass

A child pulls a toy car along a smooth fricti shown in the graph below Based on the in amount of work in joules J to pull the car Force N FORCE AND DISTANCE DATA 14 12 10 8 6

24 A 0 46 kg block is held in place against the spring by a 30 N horizontal external force The external force is removed and the block is projected with a velocity v1 1 2 m s upon separation from the spring as shown in the figure The block descends a ramp and has a velocity 12 1 5 m s at the bottom The track is frictionless between points A and B The ble enters a rough section at point B extending to E The coefficient of kinetic friction between block and the rough surface is 0 38 The velocity of the block is v3 1 4 m s at point C The block moves on to D where it stops What distance does the block travel between points B and D 0 26 m O 0 30 m 0 60 m 0 039 m 0 40 m Smooth B Rough V D

A 26 kg boulder slides down a 5 0 m high slope without tipping The boulder has zero speed at the top of the slope and has a speed of 5 8 m s at the bottom of the slope Determine the change in the thermal energy of the rock and the slope

Using the Work equation to answer the following A weight lifter is able to squat 273 kg in 1 second They started with the weight on the rack which is 1 meter off the ground and pushed the weight up to 2 5 meters off the ground in 1 second How much work did the weight lifter do First calculate the acceleration a d t Next calculate the Force F mxa Third calculate the Work W Fx d and recorded your answer below Your answer will have the units Nm newtons meters

A gallon of gas contains about 1 3 X 108 J of chemical potential energy Determine how many joules of chemical potential energy are stored in each litre of gas 3 79 L 1 gallon Calculate the height that the amount of chemical potential energy in 1 L of raise all the students in your class if it was all converted gas could to gravitational potential energy You will have to make assumptions about the mass of the students State your assumptions and show your calculations A

A 59 kg snowboarder descends a 1 3 km ski hill from the top of a mountain to the base Figure 4 The slope is at an angle of 14 to the horizontal Determine the snowboarder s gravitational potential energy relative to the mountain base when she is at the top T y 1 3 km 0 Drawing not to scale 14

drops g hockey puck rest vertically downward from a height of 1 05 m above the ice surface K TH a Determine the gravitational potential energy of the puck relative to the ice before the referee drops it b Calculate the change in gravitational potential energy of the puck as it drops from the referee s hand to the ice surface c Calculate the work done on the puck by gravity as the puck travels from the referee s hand to the ice surface

1 If a bowling ball with mass 8 0 kg travels down the lane at 2 0 m s what is its kinetic energy 16 J 2 An archor on 20

93 0 1 A bullet m speed of supported by quickly Find

8 T Marks Figure The block of mass m lies on a horizontal rough surface and is connected to a spring of force light string that passes over a frictionless pulley as shown in the constant k The system is released from rest when the spring is unstretched If the hanging block of mass m falls a distance h before coming to rest what is the coefficient of kinetic friction between the block of mass m1 and the surface k www B A block of mass 0 250 kg is placed on top of a light vertical spring of force constant 5 000 N m and pushed downward so that the spring is compressed by 0 100 m After the block is released

A worker pulls a box of mass 110 kg with constant velocity for 50 m along a horizontal floor The force the worker exerts is 500 N 37 above the horizontal Draw an FBD of the box A Determine the magnitude of the normal force and the coefficient of kinetic friction B Determine the work done by kinetic friction C Find the work done by the normal force D How much work does the worker do on the box in pulling it the first 30 m

3 The shown box is pulled on a rough horizontal surface by a force of F acting at an angle above horizontal a Which Force will do positive work b Which force will do negative work c List all the forces that there work done is Zero 0000

A stone is held at a height h above the ground. A second stone with one half the mass of the first one is held at the same height. The gravitational potential energy of the second stone compared to that of the first stone is one-fourth as much. twice as much. one-half as much. the same. four times as much.

(a) Which force does positive work? T R Fg (b) Which force does negative work? T R Fg (c) Which force does zero work? T R Fg

Water enters a pipe whose cross-sectional area is 0.96 square meter at a flow rate of 4.8 cubic meters per second and a pressure. of 92,480 pascals. The centerline of the pipe rises 8.0 meters and the cross-sectional area is increased to 1.6 square meters. The density of water is 1000 kg m-³. Find the pressure at the outlet.

A 0.33-kg particle has a speed of 5.0 m/s at point A and kinetic energy of 8.2 J at point B. (a) What is its kinetic energy at A? (b) What is its speed at point B? (c) What is the total work done on the particle as it moves from A to B?

pump lifted 50.0 kilograms of water at a constant velocity a vertical distance of 10.0 meters in 75.0 seconds. The average power consumption of the pump is (a) 6.67 W (b) 16.7 W (c) 32.7 W (d) 65.4 W

How much potential energy does a soccer ball rolling along the ground at 2 m/s have? Express your answer as a whole number of Joules: