When force and displacement are in the same direction, the kinetic energy of the body?
A.
Increases
B.
Decreases
C.
Remains constant
D.
Becomes zero
Answer: Option A
Explanation:
When force and displacement are in the same direction, the kinetic energy of the body increases. The increase in kinetic energy is equal to the work done on the body.
A bullet of mass 20g is found to pass two points 30m apart in a time interval of 4s. Calculate the kinetic energy of the bullet if it moves with constant speed.
A.
2.5J
B.
5J
C.
0.562J
D.
2J
Answer: Option C
Explanation:
Speed, v = (Distacne )/Time = 7.5m/s Kinetic energy = 1/2×0.02×7.52 = 0.5625J.
A stretched bow possesses potential energy. As soon as it is released, it shoots the arrow in the forward direction with large velocity. The potential energy of the stretched bow gets converted into kinetic energy.
Which of the following is not a conservative force?
A.
Elastic force
B.
Gravitational force
C.
Force of friction
D.
Electrostatic force
Answer: Option C
Explanation:
A force is conservative if the work done by the force in moving the particle around any closed path is zero. Therefore, force of fiction is the non conservative force.