Q. No.20 J of work is done to increase the length of a light spring by 1 cm from its natural length. Work done in increasing its length further by 1 cm is:
(1) 20 J
(2) 40 J
(3) 30 J
(4) 60 J
The work-energy theorem is the scalar form of Newton's
(1) The first law of motion
(2) The second law of motion
(3) Third law of motion
(4) All of these
A pendulum bob is made to move along a vertical circle such that it passes the highest point with critical speed. The ratio of centripetal and tangential acceleration when the string becomes horizontal is
(1) 1: 3
(2) 3: 1
(3) 1: 9
(4) 9: 1
A block of mass m is given a speed v when the spring of constant k is in its natural length as shown in the figure. The remaining kinetic energy of the block when spring is compressed by half of the maximum compression is:
(1) 25%
(2) 50%
(3) 75%
(4) Any value of less than 50%
A body of mass m moving at a certain speed suffers a perfectly inelastic collision with a body of mass M at rest. The ratio of the final kinetic energy of the system to the initial kinetic energy will be:
| 1. | \(m \over {m + M}\) | 2. | \(M \over {m + M}\) |
| 3. | \({m + M} \over m\) | 4. | \({m + M} \over M\) |
A shell fired from a cannon explodes in mid-air. It's total
(1) Linear momentum is not conserved
(2) Linear momentum is conserved
(3) Kinetic energy is conserved
(4) Potential energy is conserved
A constant force is applied on a body of mass 2 kg to give it a displacement . Work done by agent applying the force up to time t = 3 s is
(1) 3 J
(2) 9 J
(3) 18 J
(4) 2 J
A particle of mass 10 kg is moving with a velocity of m/s, where x is displacement. The work done by net force during the displacement of the particle from x = 4 m to x = 9 m is:
(1) 1250 J
(2) 1000
(3) 3500 J
(4) 2500 J
Two bodies A and B of mass m and 2m respectively are placed on a smooth floor as shown. They are connected by a spring of constant k. If a third body C of mass m moves with a velocity along the line joining A and B and collides head-on elastically with A, then speed of A at the instant of maximum compression is
1.
2.
3.
4.
1. \(\sqrt{2m^2L(g\sin\theta)^3}\)
2. \(\frac{2}{3}Lg^2\sin\theta\)
3. \(\sqrt{\frac{2}{3}m^2Lg^3}\)
4. \(mg\sqrt{2gL\sin\theta}\)
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