A small body moved along a straight line and had an impulse equal in magnitude to 8 kg * m / s.

A small body moved along a straight line and had an impulse equal in magnitude to 8 kg * m / s. At some point in time, a constant force began to act on this body, all the time directed along this straight line. In 4 s after the beginning of the action of the force, the modulus of the impulse of the body decreased 2 times. What could be the modulus of the force acting on the body?

p1 = 8 kg * m / s.

t = 4 s.

p2 = p1 / 2.

F -?

Let’s write Newton’s 2 law for a body: F = m * a, where F is the force that acts on the body, m is the body’s mass, a is the acceleration of the body.

Let us write down the formula for the acceleration of the body: a = (V2 – V1) / t, where V2, V1 are the final and initial velocity of the body, t is the time of the velocity change.

F = m * (V2 – V1) / t = (m * V2 – m * V1) / t = (p2 – p1) / t = (p1 / 2 – p1) / t = – p1 / 2 * t.

The sign “-” means that the force is directed in the opposite direction of the movement of the body, the body is inhibited.

F = 8 kg * m / s / 2 * 4 s = 1 N.

Answer: a force F = 1 N acted on the body and directed in the opposite direction of motion.