Numericals :
| Question 1 : Two bodies of equal masses are placed at heights h and 2h. Find the ratio of their gravitational potential energies. |
| Question 2 : Find the gravitational potential energy of 1 kg mass kept at a height of 5 m above the ground if g = 10 m s−2. |
| Question 3 : A box of weight 150 kgf has gravitational potential energy stored in it equal to 14700 J. Find the height of the box above the ground. (Take g 9.8 N kg− 1 ). |
| Question 4 : A body of mass 5 kg falls from a height of 10 m to 4 m. Calculate: (i) the loss in potential energy of the body, and (ii) the total energy possessed by the body at any instant? (Take g = 10 m s− 2). |
| Question 5 : Calculate the height through which a body of mass 0.5 kg is lifted if the energy spent in doing so is 1.0 J. Take g= 10 m − 2. |
| Question 6 : A boy weighing 25 kgf climbs up from the first floor at a height of 3 m above the ground to the third floor at a height of 9 m above the ground. What will be the increase in his gravitational potential energy? (Take g =10 N kg− 1). |
| Question 7 : A vessel containing 50 kg of water is placed at a height of 15 m above the ground. Assuming the gravitational potential energy at ground to be zero, what will be the gravitational potential energy of water in the vessel? (g =10 ms− 2). |
| Question 8 : A man of mass 50 kg climbs up a ladder of height 10 m. Calculate: the work done by the man, and the increase in his potential energy. (g = 9.8 m s− 2). |
| Question 9 : A block A, weighing 100 N, is pulled up a slope of length 5 m by means of a constant force F (= 100 N) as illustrated in Fig. 2.1 What is the work done by the force F in moving the block A, 5 m along the slope?What is the increase in potential energy of the block A?Account for the difference in the work done by the force and the increase in potential energy of the block. |
| Question 10 : Find the kinetic energy of a body of mass 1 kg moving with a uniform velocity of 10 m s− 1. |
| Question 11 : If the speed of a car is halved, how does its kinetic energy change? |
| Question 12 : Calculate the decrease in the kinetic energy of a moving body if its velocity reduces to half of the initial velocity. |
| Question 13 : Two bodies of equal masses are moving with uniform velocities v and 2v. Find the ratio of their kinetic energies. |
| Question 14 : A car is running at a speed of 15 km h-1 while another similar car is moving at a speed of 30 km h-1. Find the ratio of their kinetic energies. |
| Question 15 : A ball of mass 0.5 kg slows down from a speed of 5 m s-1 to that of 3 m s-1. Calculate the change in kinetic energy of the ball. |
| Question 16 : A cannon ball of mass 500 g is fired with a speed of 15 m s-1. Find: (i) its kinetic energy, and (ii) its momentum. |
| Question 17 : A body of mass 10 kg is moving with a velocity 20 m s− 1. If the mass of the body is doubled and its velocity is halved, find: the initial kinetic energy, and to the final kinetic energy. |
| Question 18 : A truck weighing 1000 kgf changes its speed from 36 km h− 1 to 72 km h− 1 in 2 minutes. Calculate :the work done by the engine, and its power. (g = 10 m s − 2). |
| Question 19: A body of mass 60 kg has the momentum 3000 kg m s-1. Calculate: the kinetic energy, and the speed of the body. |
| Question 20 : How much work is needed to be done on a ball of mass 50 g to give it a momentum of 5 kg m s − 1? |
| Question 21 : How much energy is gained by a box of mass 20 kg when a mancarrying the box waits for 5 minutes for a bus?runs carrying the box with a speed of 3 m s − 1 to catch the bus?raises the box by 0.5 m in order to place it inside the bus? (g = 10 m s − 2). |
| Question22 : A bullet of mass 50 g is moving with a velocity of 500 m s− 1. It penetrates 10 cm into a still target and comes to rest. Calculate: (a) the kinetic energy possessed by the bullet, and (b) the average retarding force offered by the target. |
| Question 23 : A spring is kept compressed by a small trolley of mass 0.5 kg lying on a smooth horizontal surface as shown in the adjacent Fig. 2.14. When the trolley is released, it is found to move at a speed of v = 2 m s − 1. What potential energy did the spring possess when compressed? |