23396.A ball is thrown vertically downwards from a height of 20 m with an initial velocity v02. It collides with the ground, loses 50 percent of its energy in collision and rebounds to the same height. The initial velocity v0 is (Take g = 10 ms–2)
10 ms–1
14 ms–1
20 ms–1
28 ms–1
23397.A bullet of mass 10 g moving horizontally with a velocity of 400 ms–1 strikes a wood block of mass 2 kg which is suspended by light inextensible string of length 5 m. As a result, the centre of gravity of the block found to rise a vertical distance of 10 cm. The speed of the bullet after it emerges out horizontally from the block will be
100 ms–1
80 ms–1
120 ms–1
160 ms–1
23398.A block of mass 10 kg moving in $x$ direction with a constant speed of 10 ms–1, is subjected to a retarding force F = 0.1$x$ J/m during its travel from $x$ = 20 m to 30 m. Its final KE will be
475 J
450 J
275 J
250 J
23399.A body of mass 1 kg begins to move under the action of a time dependent force F = 2tî + 3t2ĵ)N, where î and ĵ are unit vectors along $x$ and y axis. What power will be developed by the force at the time t?
(2t3 + 3t4) W
(2t3 + 3t5) W
(2t2 + 3t2) W
(2t2 + 4t4) W
23400.An athlete in the Olympic games covers a distance of 100 m in 10 s. His kinetic energy can be estimated to be in the range
2 × 105 J – 3 × 105 J
20,000 J – 50,000 J
2,000 J – 5,000 J
200 J – 500 J
23401.Statement–1 : Two particles moving in the same direction do not lose all their energy in a completely inelastic collision.
Statement–2 : Principle of conservation of momentum holds true for all kinds of collisions.
Statement–2 : Principle of conservation of momentum holds true for all kinds of collisions.
Statement–1 is true, Statement–2 is false
Statement–1 is true, Statement–2 is true; Statement–2 is the correct explanation of Statement–1
Statement–1 is true, Statement–2 is true; Statement–2 is the not the correct explanation of Statement–1
Statement–1 is false, Statement–2 is true
23402.A nucleus at rest splits into two nuclear parts having radii in the ratio 1 : 2. Their velocities are in the ratio
4 : 1
8 : 1
2 : 1
6 : 1
23403.A force F acting on an object varies with distance $x$ as shown here. The force is in N and $x$ in m. The work done by the force in moving the object from $x$ = 0 to $x$ = 6 m is
18.0 J
13.5 J
4.5 J
9.0 J
23404.A bob of mass M is suspended by a massless string of length L. The horizontal velocity V at position A is just sufficient to make it reach the point B. The angle θ at which the speed of the bob is half of that at A, satisfies
$\theta = \dfrac{\pi}{4}$
$\dfrac{\pi}{4}< \theta < \dfrac{\pi}{2}$
$\dfrac{\pi}{2}< \theta < \dfrac{3\pi}{4}$
$\dfrac{3\pi}{4} < \theta < \pi$