JEE PHYSICS MCQ: LAWS OF MOTION

1 Medium

1 of 1

Application +4 | -1

A ball of mass

200 \mathrm{~g}

rests on a vertical post of height

20 \mathrm{~m}

. A bullet of mass

10 \mathrm{~g}

, travelling in horizontal direction, hits the centre of the ball. After collision both travels independently. The ball hits the ground at a distance

30 \mathrm{~m}

and bullet at a distance of

120 \mathrm{~m}

from the foot of the post. The value of initial velocity of the bullet will be (if

g=10 \mathrm{~m} / \mathrm{s}^2

)

View answer and explanation

Correct option: D

360 \mathrm{~m} / \mathrm{s}

Option D (

360 \mathrm{~m} / \mathrm{s}

) is correct because the initial velocity of the bullet is calculated using the conservation of linear momentum and the distances traveled by the ball and bullet after the collision.

More Questions from LAWS OF MOTION

Practice All Chapter MCQs →

A machine gun has a mass

5 {~kg}

. It fires 50 gram bullets at the rate of 30 bullets per minute at a speed of

400 {~ms}^{-1}

. What force is required to keep the gun in position? A particle of mass

4 {~m}

which is at rest explodes into three fragments. Two of the fragments each of mass

m

are found to move with a speed of

v

each in mutually perpendicular direction. The total energy released in the process is A block of mass ‘m’ rests on a rough inclined plane making an angle

30^\circ

with the horizontal. The co-efficient of static friction between the block and the plane is 0.8. If force of friction on the block is 10 N, the mass of the block is

\left( {g = 10\,m{s^{ - 2}}} \right).

Statement-1: A shell at the origin explodes into three pieces of masses

1 \mathrm{~kg}, 2 \mathrm{~kg}

and

m \mathrm{~kg}

. The

1 \mathrm{~kg}

and

2 \mathrm{~kg}

pieces fly off with speeds

12 \mathrm{~m} / \mathrm{s}

along the

x

-axis and

8 \mathrm{~m} / \mathrm{s}

along the

y

-axis respectively. If

{m} \,\mathrm{kg}

piece flies off with speed

40 \mathrm{~m} / \mathrm{s}

, the total mass of the shell must be

3.5 \mathrm{~kg}

.
Statement-2: The law of conservation of linear momentum holds good. For a system to follow the law of conservation of linear momentum during a collision , the condition is
Total external force acting on the system is zero.
Total external force acting on the system finite and time of collision is negligible.
Total internal force acting on the system is zero. If force on a rocket having exhaust velocity of

300 \mathrm{~m} / \mathrm{sec}

is 210 N, then rate of combustion of the fuel is: