Kinematics Questions and Answers

27 The relation 3 3x 6 describes the displacement of a particle in one direction where is in in sec The displacement when velocity is zero is b 12 metres d Zero Flight of Dreams metres and a 24 metres c 5 metres

38 A ball is dropped from a bridge of 122 5 metre above a river After the ball has been falling for two seconds a second ball is thrown straight down after it Initial velocity of second ball so that both hit the water at the same time is 1 49 m s 2 55 5 m s 3 26 1 m s 4 9 8 m s

39 A boy throws balls into air at regular interval of 2 second The next ball is thrown when the velocity of first ball is zero How high do the ball rise above his hand Take g 9 8 m s 1 4 9 m 4 29 4 m 2 9 8 m 3 19 6 m

A force represented as show in figure acts on a body having a mass of 16 kg The velocity of the body at t 10 s if the body starts from rest F N A 100 m s C 49 m s 75 50 10 t S B 50 m s D 39 m s

47 A particle is dropped under gravity from rest from a height hg 9 8 m sec and it travels a distance 9 25 in the last second the height is a 100 m b 122 5 m c 145 m d 167 5 m Flight of Dreams

Two disc A and B made up of the sam material having radii a and b a rotatir about their center of mass as shown in th figure if there is no sliping between the disc then the ratio of their kinetic energies w be b OG a 2 a b b a

has the Note that in one direction as shown the acceleration of an object are always along the same straight line either in the same di rection or in the opposite direction However for motion in two or three dimensions veloc ity and acceleration vectors may have any angle between 0 and 180 between them dimension the ve velocity and 8

U1 Two particles A and B move with constant velocities v and along two straight lines inclined at angle 0 towards the intersection point O At the moment t 0 the particles were located at the distance 1 and 1 from the point O as shown in the figure Find the shortest distance between the particles U V B

A man can swim with a velocity v relative to water and can run on the ground with a velocity w The flow velocity of the river is u The width of the river is d The man is at a point A on one bank and wants to reach point B lying right across on the other bank of the river as shown in the figure Find the minimum time in which the man can reach the destination d B

53 Predict the motion of an object on the basis of given information i Change in the speed of the object is zero and its direction of motion is fixed ii Change in the velocity of the object is zero during any time interval iii Change in the speed of the object is not zero but its direction of motion is fixed

A particle starts from rest with zero initial acceleration The acceleration increases uniformly with time Find the time average and distance average of velocity upto a certain instant when the velocity becomes v

A man standing on a horizontal road holds an umbrella a 30 with the vertical to keep himself dry He then runs at speed of 10 m s and find the rain drops to be hitting vertically The velocity of rain w r t man is 20 m s 30 m s 10 m s 5 m s

2 9 When brakes are applied the speed of a train decreases from 96 kmh 1 to 48 kmh 1 in 800 m How much further will the train move before coming to rest Assuming the retardation to be constant 266 66

8 A ladder 3m in length and weighing 200N is placed on a rough wall at an inclination of 60 as shown Coefficient of friction between ladder and wall is 0 28 and between ladder and floor is 0 34 A man weighing 600N is to reach to the top of the ladder Calculate the horizontal force to be applied to the ladder at floor level to prevent the ladder from slipping 600N 200N

A block of mass mis attached with a massless spring of force constant k The block is placed over a fixed rough inclined surface for which the coefficient of friction is The block of mass mis initially at rest The block of mass Mis released suddenly from rest with spring in unstretched state The minimum value of M required to move the block up the plane is neglect mass of string and pulley and friction in pulley J m 37 3 5 m mmmm M

When a deer was 48 m from a leopard the leopard starts chasing the deer and the deer immediately starts running away from the leopard with constant velocity A leopard cannot run at high speeds for a long time and has to slow down due to fatigue If we assume that the leopard starts with an initial speed of 30 m s and reduces its speed in equal steps of 5 m s after every 2 s interval at what minimum speed must the deer run to escape from the leopard