Question

Q.7 Aresultant force of 20 N acts on an object of mass 4 kg for 10 m. Find the final speed if the initial speed is 5 m/s.​

Answer 1

Answer:

From F = ma, 20 = 4a so a = 5m/s^2

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 = 5m/s, a = 5m/s^2, s = 10m, and we want to find v, so we use equation (2):

v^2 = u^2 + 2as

v^2 = 5^2 + 2(5)(10)

v^2 = 125

So, v = √125 = 11.18

The final velocity is 11.18m/s