Question

a runner accelerates from 0 m/s to 5 m/s in 10 seconds. what is the runner's acceleration?

Answer 1

A runner accelerates from rest at a constant rate of 3.0m/s^2 for 5.0 s. How fast is she running now?

Galaxy Unpacked.

A runner accelerates from rest at a constant rate of 3.0m/s^2 for 5.0 s. How fast is she running now?

Let’s review the 4 fundamental kinematic equations of motion for constant acceleration (strongly recommend you commit these to memory – they will serve you well):

s = ut + ½at^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 know u = 0, a = 3.0m/s^2, t = 5.0s, and we want to know v, so we use equation (3)

v = u + at

v = 0 + 3.0(5.0) = 15

The runner is now moving at 15m/