Question

a body of mass 3 kg uniformly retards from 40 metre per second to 10 metre per second in 10 seconds find the retarding force​

Answer 1

Answer:

-15 N

Explanation:

According to the given question,

m = mass = 3 kg

u = initial velocity = 40 m/s

v = final velocity = 10 m/s

t = time = 10 sec

F = force and a = acceleration

And we are asked to find the force, but for force we need mass and acceleration. As mass is already given then we have to find acceleration.

We know,

• v = u+at

Putting the values we get,

• 10 = 40 + 10a

• 10a = 10-40

• 10a = -30

• a = - 30/10

• a = - 3 m/s^2

Thus acceleration is - 3 m/s^2. Here negative sign indicates that acceleration is opposite to the direction of motion of body i.e, deceleration.

Again, from Newton's 2nd law,

• F = ma

Putting the values we get,

• F = 3×(-5)

• F = - 15 N

Thus force is -15 N means force is opposite to the direction of motion.

As force is vector quantity we have to consider sign strictly.