1) Which of the following statements is correct? a) If there is no friction, work to be done to move a body up an inclined plane will be zero. b) If there is no friction, moving vehicles can not be stopped even by locking the brakes. c) As the angle of inclination is increased, the normal reaction on the body placed on it increases. d) Friction increases the time taken by a body projected upwards to reach the highest point 2) A man of mass 60 kg climbs up a 20 m long stair case to reach the top of a building, which is 10 m high. What is work done by him? a) 12 KJ b) 3 KJ c) 6 KJ d) 30 KJ 3) A car running at 25 km/h can be brought to rest by applying brakes at a distance of 0.5 m. If the car is running at 75 km/h, how far will it go before coming to rest, if the braking force remains the same? a) 1m b) 2m c) 3m d) none 4) A gun fires bullets each of mass 20 g with a speed of 2 km/s. The person firing the gun experiences a recoil force of 800 N. What is the number of bullets fired per second? a) 3 b) 4 c) 5 d) 16 5) A vehicle is moving on a horizontal road at a constant speed of 10 m/s. The engine needs to spend 5 KJ of energy per second. What is the force on the vehicle? a) 50 KN b) 5 KN c) 0.5 KN d) 0.05 KN 6) Which of the following remains constant for an isolated system? a) Sum total of kinetic energy and potential energy b) Kinetic energy c) Kinetic energy and mechanical energy d) Potential energy 7) An engine pumps out 40 kg of water in one second. The water comes out vertically upwards with a velocity of 3ms-1. What is the power of engine in kilowatt? a) 1.2 KW b) 12 KW c) 120 KW d) 12000 KW 8) A body of mass M is lowered with acceleration g/2 with the help of a string and through a distance l. What is the work done by the string? a) Mgl b) 3 Mgl/2 c) Mgl/2 d) Mg1/4 9) A ball of mass 2 kg moves so that its position x as function of time t is given by x = t3/3. If x is measured in metres and 't' in seconds, what is the kinetic energy acquired by the particle in first two seconds? a) 16 KJ b) 1.6 J c) 16 J d) 1.6 KJ 10) A body is under the action of two equal and opposite forces, each of 3N and is displaced by 2 m. Which of the following is the value of work done by the body? a) + 6 KJ b) zero c) 3 KJ d) -6 J 11) Which of the following increases with rise in ball that is projected upwards? a) Momentum b) Retardation c) Kinetic energy d) Potential energy 12) A bullet is fired into a block. Its velocity decreases by 50%, when it penetrates through 9 cm. What will be the total distance penetrated by the bullet? a) 10cm b) 12cm c) 15cm d) 8cm 13) To move a body along a curved horizontal path, several force varying magnitudes and directions are applied on the body. Initially, the body was at rest. The work done on the body will be equal to a) total energy of the body irrespective of path b) total kinetic energy of the body irrespective of path c) total energy or total kinetic energy depending on the nature of path d) total energy or total kinetic energy depending on the nature of path and magnitude of resultant force 14) A simple pendulum is vibrating in an evacuated chamber. It will oscillate with a) constant amplitude b) decreasing amplitude c) increasing amplitude d) amplitude, the variation of which cannot be predicted 15) What is the kinetic energy, if the momentum of a body is doubled? a) It will be halved. b) It will remain the same. c) It will be doubled. d) It will be increased four times.

physics ch. force

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