UFM Mechanics

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jee-main 2020 Q22 View
A thin rod of mass 0.9 kg and length 1 m is suspended, at rest, from one end so that it can freely oscillate in the vertical plane. A particle of mass 0.1 kg moving in a straight line with velocity $80\,\mathrm{m\,s^{-1}}$ hits the rod at its bottom most point and sticks to it (see figure). The angular speed (in $\mathrm{rad\,s^{-1}}$) of the rod immediately after the collision will be $\_\_\_\_$
jee-main 2021 Q3 View
Two billiard balls of equal mass 30 g strike a rigid wall with same speed of 108 kmph (as shown) but at different angles. If the balls get reflected with the same speed, then the ratio of the magnitude of impulses imparted to ball $a$ and ball $b$ by the wall along $X$ direction is:
(1) $1 : 1$
(2) $\sqrt{2} : 1$
(3) $2 : 1$
(4) $1 : \sqrt{2}$
jee-main 2022 Q3 View
A ball of mass 0.15 kg hits the wall with its initial speed of $12 \mathrm{~m~s}^{-1}$ and bounces back without changing its initial speed. If the force applied by the wall on the ball during the contact is 100 N, calculate the time duration of the contact of ball with the wall.
(1) 0.018 s
(2) 0.036 s
(3) 0.009 s
(4) 0.072 s
jee-main 2022 Q4 View
A block of metal weighing 2 kg is resting on a frictionless plane (as shown in figure). It is struck by a jet releasing water at a rate of $1 \mathrm {~kg} \mathrm {~s} ^ { - 1 }$ and at a speed of $10 \mathrm {~m} \mathrm {~s} ^ { - 1 }$. Then, the initial acceleration of the block, in $\mathrm { m } \mathrm { s } ^ { - 2 }$, will be
(1) 3
(2) 6
(3) 5
(4) 4
jee-main 2022 Q23 View
A batsman hits back a ball of mass 0.4 kg straight in the direction of the bowler without changing its initial speed of $15 \mathrm {~m} \mathrm {~s} ^ { - 1 }$. The impulse imparted to the ball is $\_\_\_\_$ Ns.
jee-main 2023 Q4 View
An average force of 125 N is applied on a machine gun firing bullets each of mass 10 g at the speed of $250 \mathrm{~m}\mathrm{~s}^{-1}$ to keep it in position. The number of bullets fired per second by the machine gun is:
(1) 50
(2) 25
(3) 100
(4) 5
jee-main 2023 Q6 View
A bullet of 10 g leaves the barrel of gun with a velocity of $600 \mathrm{~m~s}^{-1}$. If the barrel of gun is 50 cm long and mass of gun is 3 kg, then value of impulse supplied to the gun will be:
(1) 6 N s
(2) 3 N s
(3) 36 N s
(4) 12 N s
jee-main 2024 Q5 View
A spherical body of mass 100 g is dropped from a height of 10 m from the ground. After hitting the ground, the body rebounds to a height of 5 m . The impulse of force imparted by the ground to the body is given by: (given $g = 9.8 \mathrm {~m} \mathrm {~s} ^ { - 2 }$ )
(1) $4.32 \mathrm {~kg} \mathrm {~m} \mathrm {~s} ^ { - 1 }$
(2) $43.2 \mathrm {~kg} \mathrm {~m} \mathrm {~s} ^ { - 1 }$
(3) $23.9 \mathrm {~kg} \mathrm {~m} \mathrm {~s} ^ { - 1 }$
(4) $2.39 \mathrm {~kg} \mathrm {~m} \mathrm {~s} ^ { - 1 }$
jee-main 2024 Q5 View
A simple pendulum of length 1 m has a wooden bob of mass 1 kg. It is struck by a bullet of mass $10 ^ { - 2 } \mathrm {~kg}$ moving with a speed of $2 \times 10 ^ { 2 } \mathrm {~m} \mathrm {~s} ^ { - 1 }$. The bullet gets embedded into the bob. The height to which the bob rises before swinging back is. (use $g = 10 \mathrm {~m} \mathrm {~s} ^ { - 2 }$)
(1) 0.30 m
(2) 0.20 m
(3) 0.35 m
(4) 0.40 m