Newton's law of motion Questions and Answers

On a large slippery ground a boy left his dog sitting and walks away with a constant velocity Ub 2 0 m s When he is xo 199 m away from the dog the dog decides to catch him and thereafter move together The dog cannot develop acceleration more than a 2 0 m s in any direction In what minimum time will the dog meet the boy

A block is placed on an inclined plane moving towards right horizontally with an acceleration aog The length of the plane AC 1 m Friction is absent everywhere Find the time taken in seconds by the block to reach from C to A dong A B 37

In the system shown wedge of mass 5 M The pulleys are ideal and the cords are there is friction inextensible anywhere M 5M 2M A initial acceleration of wedge is C tension in string is B initial acceleration of wedge is D tension in string is no 14 mg 25 17 mg 25 3g 25 2g 25

3 A uniform rope of length 10 cm and mass 15 kg hangs vertically from a rigid support A block of mass 5kg is attached to the free end of the rope A transverse pulse of wavelength 0 08 m is produced at the lower end of the rope The wavelength of the pulse when it reaches the top of the rope will be a 0 08 m c 0 16 m b 0 04 m d 0 m 15 kg 5kg

3 14 Give examples of a one dimensional motion where a the particle moving along positive x direction comes to rest periodically and moves forward b the particle moving along positive x direction comes to rest periodically and moves backward

Paragraph for Questions 9 and 10 For the given system of blocks and a concave mirror answer the following Assuming A B C are very small Focal length of mirror is 20 cm y A Cure B Mark the CORRECT statement s A Speed of A is 8 m s when C is moving down with speed 8 m s B Speed of B is 8 m s when C is moving down with 8 m s C Speed of A is 12 m s when C is moving down with 8 m s D Speed of A is 12 m s when C is moving down with 12 m s 0 Mark the CORRECT statement s C X A When A is at x 30 cm image is at x 60 cm B When A is at x 30 cm image is at x 60cm C When C moves with a speed 8 m s downwards image of A moves with a speed 12 m s D When C moves with a speed 8 m s downwards image of A moves with a speed 48 m s

A dynamometer D which is a device used to measure force is attached to two blocks of masses 6 kg and 4 kg Forces of 20 N and 10 N are applied on the blocks as shown in the figure The reading of the dynamometer is 6 kg D 4 kg

Two fixed frictionless inclined plane making an angle 30 and 60 with the vertical are shown in the figure Two blocks A and B are placed on the two planes What is the relative vertical acceleration of A with respect to B 60 B 30

Q6 For the bar shown in figure 4 calculate the reaction produced by the lower support on the bar Take E 200 GN m2 Find also the stress in the bars 1 2m m N 55 KN R A 110 mm A 220 mm 1 2m Figure 4 30 cm B 30 KN 20 KN 20 cm Figure 5 10 cm D 15 KN

A ball of mass 1 kg dropped from 9 8 m height strikes the ground and rebounds to a height of 4 9 m If the time of contact between ball and ground is 0 1 s then find impulse and average force acting on ball COLLOXWIN PA

kept horizontally One end of the plank is now lifted so that it gets tilted making an angle 0 from the horizontal as shown in the figure below The maximum value of 0 so that the football does not start rolling down the plank satisfies the figure is schematic and not drawn to scale Plank a sin 8 r R b tan 8 r R c sin r 2R 2r R 0

with a light string which passes over a massless pulley as shown in figure The magnitude of acceleration of centre of mass of both the blocks is neglect friction everywhere A 3 1 Correct Answer B 3 1 g 802 60 D 3 1

A uniform ladder AB whose weight is 600 N and length 4 metres rests against a smooth vertical wall making with it an angle of 30 The other end rests on the ground surface Find the reactions given to the ladder by the wall and the floor and their inclination to the vertical when a man weighing 700 N climbs the ladder by a distance 1 5 m along the length of the ladder

31 A uniform rope having mass m hangs vertically from a rigid support A transverse wave pulse is produced at the lower end The speed u of wave pulse varies with height h from the lower end as a c h h b d h h

A man is dragging a trunk up the loading ramp of a mover has a slope angle of 20 0 and the man pulls upward with direction makes an angle of 29 5 with the ramp 20 0 a How large a force is necessary for the componen ramp to be 52 0 N

YOU DIDN T ATTEMPT ABCD is a rectangle forces of 9N 8N 3N act along the lines DC CB and BA respectively in the directions indicated by the order of the letters Then the resultant force is 9N D A 8 N 5 N 20 N 3N C 8N B