A body of mass 4kg is acted on by a constant force of 12N for 3 seconds. The kinetic energy gained by the body at the end of the time is

Answer Details

The kinetic energy gained by a body is equal to the work done on it by a force, as given by the formula:
Kinetic energy gained = work done = force x distance
In this problem, the force acting on the body is constant at 12N, and it acts for a time of 3 seconds. We can find the distance moved by the body using the formula for distance travelled by an object under constant acceleration:
Distance = (1/2) x acceleration x time^2
Since the force on the body is constant, we can use Newton's second law to find its acceleration:
Force = mass x acceleration
Acceleration = Force / mass = 12N / 4kg = 3 m/s^2
Using this acceleration, we can find the distance travelled by the body:
Distance = (1/2) x 3 m/s^2 x (3 s)^2 = 13.5 m
Now, we can use the formula for work done to find the kinetic energy gained by the body:
Work done = force x distance = 12N x 13.5m = 162 J
Therefore, the correct answer is 162J.