Physics Chapter 2 Entry test MCQs
26. The velocity and momentum of a moving body are 10,000 cm s-1 and 10,000 g cm s-1 respectively. The K.E will be
a. 5 x10-2 J
b. 5 x107
c. 5 x 10° J
d. 5 x 105 J
27. If momentum of a moving object is doubled then its kinetic energy will be
a. Halved
b. Doubled
c. Same
d. Four times
28. The momentum and kinetic energy of a ball is numerically equal. The numerical value of velocity is
a. 2m s-1
b. 1ms-1
c. 4ms-1
d. 3m s-1
29. Kinetic energy of a body moving with speed of 10ms-1 is 30 J. If its speed becomes 30m/s its K.E will be
a. 180 J
b. 10 J
c. 270 J
d. 90 J
30. Car X is traveling at half the speed of car Y. Car X has twice mass of car Y. Which statement is correct?
a. Car X has one quarter of the kinetic energy of car Y
b. Car X has half the kinetic energy of car Y
c. The two cars have the same kinetic energy
d. Car X has twice the kinetic energy of car Y
31. A ball of mass 2 kg and another of mass 4 kg are dropped together from a 60 feet tall building. After a fall of 30 feet each towards earth, their respective kinetic energies will be in the ratio of
a. 1:4
b. √2 : 1
c. 1 : √2
d. 1:2
32. A bomb of mass 30kg at rest explodes into two pieces of masses 18 kg and 12 kg. The velocity of 18 kg mass is 6 ms-1. The K.E of other mass is
a. 486 J
b. 324 J
c. 524 J
d. 256 J
33. The kinetic energy acquired by a body of mass m is travelling some distance s, starting from rest under the actions of a constant force, is directly proportional to
a. m2
b. m°
c. m1/2
d. m
34. When force and displacement are in the same direction, the kinetic energy of the body
a. Decreases
b. Increases
c. Becomes zero
d. Remains constant
35. A truck and a car are moving with equal velocity. On applying brakes, both will stop after a certain distance, then?
a. Truck will cover less distance before stopping
b. Both will cover equal distance
c. Car will cover less distance before stopping
d. None of the mentioned
36. Potential energy per unit volume is given by
a. mgh/p
b. mgh
c. pgh
d. gh
37. A body is falling from a height h. After it has fallen a height h / 2 it will possess
a. Only kinetic energy
b. Only potential energy
c. More kinetic and less potential energy
d. Half potential and half kinetic energy
38. Energy stored in the spring of watch is
a. Kinetic energy
b. Electrical energy
c. Elastic potential energy
d. potential energy
39. Initially four identical uniform block, each of mass m and thickness h, are spread on a table, work require to stack them on one another is
a. 3mgh
b. 1mgh
c. 6mgh
d. 4mgh
40. A stone is thrown up from the surface of earth when it reaches at maximum height. Its total energy is equal to
a. Zero
b. mgh
c. 2 mgh
d. 1/2 mv2
41. Energy consumed by 60-watt bulb in 2 minutes is equal to
a. 720 joules
b. 7.2 kilo joules
c. 72000 joules
d. 120 joules
42. The consumption of energy by 60-watt bulb in 2 seconds is:
a. 120 J
b. 20J
c. 0.02 J
d. 30J
43. 100 joules work has been done by an agency in 10 seconds. What is power of agency?
a. 100
b. 1000-watt
c. 0.10 watt
d. 10 watt
44. A 500N force is applied on an object and it moves with velocity 10ms-1. If value of power is 2500 watt. Then what will be the angle between force and displacement
a. 60°
b. 0°
c. 23°
d. 90°
45. The time taken by an engine of power 10 kW to lift a mass of 200 kg to the height of 40 m is
a. 4 s
b. 2 s
c. 16 s
d. 8 s
46. To travel at a constant speed, a car engine provides 24 kW of useful power. The driving force on the car is 600 N. At what speed does it travel?
a. 4ms-1
b. 25ms-1
c. 0.4ms-1
d. 2.5ms-1
47. A force of 1000 N is needed to lift the hook of a crane at a steady velocity. The crane is then used to lift a load of mass 1000 kg at a velocity of 0.5ms-1 How much of the power developed by the motor of the crane is used in lifting the hook and the load? (Take gas 10ms-2 )
a. 20 kW
b. 5.0 kW
c. 22 kW
d. 5.5 kW
48. The power output of a lamp is 6W. How much energy does the lamp give out in 2 minutes?
a. 120 J
b. 3 J
c. 430 J
d. 720 J
49. A man M1 of mass 80 kg runs up a staircase in 15 s. Another man M2 also of mass 80 kg runs up the same staircase in 20 s. The ratio of the power developed by them will be:
a. 4/3
b. 1
c. 16/9
d. none of these
50. An engine pumps up 100 kg of water through a height of 10 m in 5s. Given that the efficiency of the engine is 60%, what is the power of the engine? (Take g = 10ms-2 )
a. 3.3 kW
b. 33 kW
c. 0.033 kW
d. 0.33 kW