Kinematics Questions and Answers

4 33 A ball 4 of mass 10 kg and a ball B of unknown mass are placed on a horizontal frictionless table which rest against a rigid wall as shown in figure 4 135 The ball A moves towards the ball B with a velocity v What should be the mass of B such that both A and B move with the same speed after A has undergone a collision with ball B and the wall All collisions are assumed to the elastic B O O Figure 4 125 k be A 4 SL SI b

4 33 A ball A of mass 10 kg and a ball B of unknown mass are placed on a horizontal frictionless table which rest against a rigid wall as shown in figure 4 135 The ball A moves towards the ball B with a velocity v What should be the mass of B such that both A and B move with the same speed after A has undergone a collision with ball B and the wall All collisions are assumed to the elastic Ans 30 kg B O O Figure 4 135

A boat crosses a river from port A to port B which are just on the opposite side The speed of the water is V and that of boat is V relative to still water Assume V 2V What is the time taken by the boat if it has to cross the river directly on the AB line D width of the river B W D VB 2 d a 2D VB 3 b 3D 2V c 2019 D 2 VB

The equation of a projectile is y 3x x The angle of a c tan 0 EN projection is given by 1 3 gx b tan0 3 2 2020 d zero velocity u making a

Determine static indeterminacy of the truss given in Figure 1 Using method of secti find the forces in GH and GC member Assume suitable data 6 0 Marks 30 kN H 5x6m D 8 m 60 kN

A man drives a car from station B towards station A at speed 60 km h A car leaves station A for station B every 10 min The distance between A and B is 60 km The car travels at the speed of 60 km h A man drives a car from B towards A at speed of 60 km h If he starts at the moment when first car leaves the station B then how many cars would be meet on the route a 4 b 7 c 9 2019 d 12

19 10 A wheel of radius rolls with slipping with linear speed vand angular velocity o lump of mud separates from the wheel at its highest point B and drops at point C on the road The distance AC will be B O 1 A V 10 LO 3r on a horizontal road as shown in figure When it is at point A on the road a sr

ctively e force 2 80 A ball is held at rest in position A by two light cords The horizontal cord is now cut and the ball swings to the position B What is the ratio of the tension in the cord in position B to that in position A originally A 3 C 1 2 A 30 30 Figure 2 178 B 3 4 D X B

A stone is projected upward with a velocity of 20 ms The air resistance is caused of deceleration of 2 m Then Given Air resistance always act opposite to the direction of motion a The maximum height attained by the stone is 16 67 m p The time of flight of stone is 3 7 s The speed with which it will strike with ground is zero d The acceleration during down motion is 8 ms iple options may be correct

A car moving along a straight line covers one third of the total distance with speed v and the remaining distance with speed 2v What will be the average speed of the car over the entire distance A V B 2v C 3v 2

A rubber ball is released from a height of 4 90 m ab the floor It bounces repeatedly always rising 81 100 of the height through which it falls a Ignoring the practical fact that the ball has a finite size in other words treating the ball point mass that bounces an infinite number times show that its total distance of travels 46 7 m

Three bodies A B and C are projected with three different velocities UA UB uc The maximum height attained by A B and C is same as shown in the figure above Choose the correct statement A C A UA UB uc B UA UB uc C UA UB uc

A car traveling at 101 0 km hh tree The front of the car is compressed and the driver com rest after traveling 5 0 m What the average acceleration of the driver during the collision Write your answer to two decimal pla as a multiple of gravity q

A thief in a stolen car crashes through a police check post at his top speed of 90 km h A motorcycle cop reacting after 2 s accelerates from rest at 5 m s2 his top speed being 108 km h The distance from the check post at which the thief is caught is k x 250 m then k is ARISSAER

A stone is thrown upward with velocity 25 ms 1 Another stone is simultaneously thrown downward from the same point with the speed 10 ms 1 When the first stone is at a height 10 m The relative velocity of first stone w r t second stone is m s

A bus appears to go with a speed of 25 km hr to a car driver driving at the rate 7 km hr northwards If the bus actually travels in east direction its speed is 1 24 km h 2 23 km h 3 26 km h 4 30 km h displacement vector of magnitude 4 makes an angle 30 with the x axis Its rectangular components in

A stone is dropped from a balloon at an altitude of 480m If the balloon ascends with a velocity of 20m s and descends with a velocity of 20 m s times taken by the stone to reach the ground in the two cases respectively are g 10m s a 8s and 12 s b 8 s and 10 s d 12 s and 8 s c 8 s and 8 s

3 O A body lying initially at point 3 7 starts moving with a constant acceleration of 41 Its position after 3 s is given by the co ordinates 1 7 3 3 21 7 2 7 18 4 3 7 nition of an object at rest is given by 31 8 It moves with constant acceleration and reaches

A block of mass 10kg is at rest on a rough inclined surface of angle of inclination 30 If coefficient of friction between block and inclined surface is 0 8 then the force applied by inclined surface on block is g 10m s

32 The coordinates of a moving particle at an arbitrary time t are given by x ct and y bt2 where c and b are given constants The velocity of the particle is A 2t c b C t c b D 2t c b A particle of mass m having angular momentum L is moving in a circular path of radius r The centripetal force on the particle is A L 2 2 mr cb b c B 2t B mr C L mr D L mr

3 21 7 17 The initial position of an object at rest is given by 31 8 It moves with constant acceleration and reaches to the position 21 4 after 4 s What is its acceleration 2 21 1 1 1 3 1 3 1 8 2 4 81 31 12 1 71 Velocity of B as observed by A is

The vector joining the points A 1 1 1 and B 2 3 4 and pointing from A to B is A i 4j 5k B i 41 5k C i 4j 5k A particle is moving with speed 6 m s along the 211 21 D 1 41 5k

2 18 A car starts moving along a line first with acceleration a 5 ms starting from rest then uniformly and finally decelerating at the same rate a and comes to rest The total time of motion is 25 s The average speed during the time is 20 ms How long does particle move uniformly b 12 so a 10 s c 20 s 15 s ont r of a particle depends on tim

Example A uniform ladder of length 2L and mass m leans against a wall in a vertical plane at an angle e to the horizontal The floor is rough having a coefficient of static frictionu A person of mass M stands on the ladder at a distance D from its base see figure If the wall is frictionless the maximum distance Dmax up the ladder that the person can reach before the ladder slips is 2L S

A ball of mass 0 15 kg is dropped from a height 10 m strikes the ground and rebounds to the same height The magnitude of impulse imparted to the ball is g 10 m s2 nearly 1 4 kg m s 108021 41 0 kg m s 4 2 kg m s 2 1 kg m s 1 2 3 4 2x 15 x tood so 306 1 4 100

A car starts from rest and accelerates at 5 m s At t 4 s a ball is dropped out of a window by a person sitting in the car What is the velocity and acceleration of the ball at t 6s Take g 10 m s 1 20 2 m s 10 m s 2 3 20 m s 5 m s 20 m s 0 20 5 m s 0

iv If B and C are at the same level on trajectory and the time difference between these two points is t similarly A and D are also at the same level and the time difference between these two positions is t then 12 1 8h 8 h 0 A B D X

A 72 J B 14 4 J C 86 4 J D 864 J 37 A particle is moving in a vertical circle of radius r In order to stay on the circle the minimum velocitie at the highest and lowest points of its path are respectively A gr 5gr B 5gr gr C 2gr 5gr D 5gr 2gr

D Depends on the strength of the dipole 2 A particle starting from rest moves with uniform acceleration a for some time Then it undergo uniform declaration 3 and comes to rest If the total time is t the maximum velocity of the particle A a 2t B a a C a B t D a a t

From the top of an inclined plane of inclination 30 with the horizontal a body is thrown horizontally with a speed of 3 ms If the body lands exactly at the foot of the in cline find the angle with the horizontal at which the body lands H 3ms 30 R 2 a I

hree blocks of masses 2 kg 3 kg 4 kg are placed as shown in the figure Coefficient of friction between the surfaces are 0 2 0 5 0 0 A horizontal force is applied on 3 kg block 0 2 0 5 0 2 kg 3 kg 21 N 4 kg Choose the correct answer 1 The maximum horizontal force for which no sliping takes place between the blocks when the force is applied on 3 kg block is 3 1 15 N 2 18 N B 4 24 N

17 A particle is moving along a circular path of radius 10 m 17 1010 er a tot and with a uniform speed 10 m s What will be the average acceleration when the particle completes half revolution 1 m s 20 2 m s 7t 3 10 m s 4 zero after 10 1 m s U itera ca a 20 2 m s R 3 10 m s 4 zero

A 4 mg B 2 mg 40 A particle moving in a straight line travels the first t sec with velocity v and the next t sec with velocity The average velocity of the particle over the time interval 2t sec is A V1 1 2 2 3 C mg B VIV C V1 V2 V1 V2 D mg m D 21112 11 12

Q10 A body moving with velocity is stopped by the application of brakes after covering a distance If the same body moves with velocity nu and same braking force is applied on it then it will come to rest after covering a distance of Remember the result as a standard result a ns b n s c s n d s n

Two blocks A and B of masses 5 kg and 10 kg is contact with each other rest on a table against a rigid partition as shown in figure The coefficient of friction between the blocks and the table is UK 0 10 A force of 195 N is applied horizontally at A If F be the contact force between the blocks A and B when partition is in place F is the contact force between A and B when partition is removed F The ratio F 1 3 is 195 N A B 2 2

Two balls of masses M and m are attached to two threads of length 1 such that the two threads are suspended at the same point The balls are both deflected to the horizontal position of the threads released from rest at the same time and they collide head on The collision is perfectly elastic If the ball of mass m reaches the maximum height which is allowed M m can be A 0 5 C 2 B 1 5 D 2 5 M

Two points A and B are located on the ground a certain distance d 10 2m apart Two rocks are launched simultaneously from points A and B with equal speeds but at different angles Each rock lands at the launch point of the other Knowing that one of the rocks is launched at an angle 8 37 with the horizontal what is the minimum distance between the rocks during the flight given cos 37 3 5

An insect moves with a constant velocity v from one corner of a room to other corner which is opposite of the first corner along the largest diagonal of room If the insect can not fly and dimensions of room is axa xa then the minimum time in which the insect can move is times the square a V root of a number n then n is equal to

A projectile is fired with a velocity u at right angle to the plane which is inclined at angle 0 with the horizontal The horizontal displacement along x of the projectile is 1 3 tane g 4 20 tane X 2 4 24 g 4 tane tane 2

4 None of these 4 A car starts from rest with a constant acceleration a for some time and attains a velocity vo Then it immediately retards at a constant rate a2 to rest The total time of journey is to Identify the correct velocity time graph 3 Vo Vo to V 3 V t 5 For the above situation let t be the time of accelerated motion and to be the time of retarded motion then the correct relation is a a a a 1 a t a t 2 a t a t 4 a t 2 a t 3 a t a t 6 The correct relation between vo a a and to is a a 2 2 4 to V Type Text a a a a 4 v aa t 2 V Id your responses to Comprehension Il A rocket is fired upwards such that its engine takes 10 s to explode fully Its velocity time graph is as shown in the figure Acceleration due to gravity is 10 m s v m s 1 3 2 3 4 1000 Choose the correct answer The total time for which the rocket moves upward is 1 10 s 3 110 s The height reached by the rocket till its engine explodes is 1 1000 m 3 10 000 m t s 2 100 s 4 20 s 2 5000 m 4 20 000 m The maximum height attained by the rocket is 1 5000 m 2 50 000 m 3 55 000 m 4 100 000 m sked by 3525574 aesl id Standard XI Stream JEE Jul 27 2021 at 6

A projectile is thrown up with initial speed u at 9 with the horizontal It just crosses a horizontally The tower is 100 m high and the f the tower is at 200 m from the point of proje The angle of projection is 1 30 2 45 3 60 4 70

35 Two ships are 10 km apart on a line running south to north The one farther north is steaming west at 40 km hr The other is steaming north at 40 km hr What is their distance of closest approach in km and how long do they take to reach it 1 3 10 1 hr 2 4 10 1 22 hr 10 2 28 4 18 20 1 28 hr hr

19 The position at time t of a particle moving in a straight line is given by x 2t 1 3t The acceleration of the particle is 20 A 2 B 6 C 3 D 12 If the distance between two charges of the same sign is decreased the electrostatic potential energy

eastward direction and 50 2 m in south west in total time 10 s The average velocity of particle is Covers 50 m in northward direction 40 m A in 1 2 ms 1 eastward 2 2 ms 1 westward 3 1 ms westward 4 1 ms 1 eastward

The coofficient of static friction between the blocks shown in figure is and the table smooth What maximum horizontal force F be applied to the block of mass A so that blocks move together 7777777 1 Mug 3 m m M 2 m M g 2 4 2019

A small particle is projected from the bottom of an inclined plane of inclination 30 with velocity of 40 m s at an angle of 60 with horizontal If the speed of the particle in m s to nearest integer when its velocity vector is parallel to the plane is 20 v then find v g 10 m s Asked by 2045114 aesl id Standard XI I Stream NEET I Sep 12 2021 at

xample 11 An object accelerates uniformly from initial velocity u to final velocity v It travels distance s straight line in time t Then check the dimensional consistency of the following equations Wh of them are correct dimensionally Vav u V 3 ii s ut at iii v u 2s

A block is thrown with a velocity of 2 ms relative to ground on a belt which is moving with velocity 4 ms in opposite direction of the initial velocity of block If the block stops slipping on the belt after 4 sec of the throwing then choose the correct statements s A Displacement with respect to ground is zero after 2 66 and magnitude of displacement with respect to ground is 12 m after 4 sec B Magnitude of displacement with respect to ground in 4 sec is 4 m Magnitude of displacement with respect to belt in 4 sec is 12 m Displacement with respect to ground is zero in 8 3 sec

A projectile is fired at such an angle as to have ma maximum height attained by it g 9 8 m s 1250 m A projectile shot out at an angle of 35 strikes the ground at a horizontal distance of 4 km from the point of projection Calculate 1 the initial velocity 2 time of flight 3 maximum altituc 4 velocity at the point of maximum altitude 204 m s 23 9 s 698 5 m 167 m

ground in 3s From what height was it thrown and what is its horizontal range g 9 8 m 44 1 m 75 16 A body thrown horizontally from the top of a building with a velocity of 10 m s f 30 m away from the building What is the height of the building g 9 8 m s 44 1