Question

A object of mass 10 kg moving with a speed of 15mls hits the wall and comes to rest within 0.03 second . calculate the impulse and average force acting on the object.​

Answer 1

Answer:

Let’s review the 4 basic kinematic equations of motion for constant acceleration (this is a lesson – suggest you commit these to memory):

s = ut + ½ at^2 …. (1)

v^2 = u^2 + 2as …. (2)

v = u + at …. (3)

s = (u + v)t/2 …. (4)

where s is distance, u is initial velocity, v is final velocity, a is acceleration and t is time.

In this case, we have u = 15m/s, v = 0, t = 3s and we want to find acceleration, a, so we use equation (3) v = u + at

0 = 15 + 3a so a = -5m/s^2 (the negative meaning deceleration)

Then from F = ma,

F = 10kg(-5m/s^2) = -50N

So the required force is 50N in the direction opposing the initial velocity.