A penny mass=.004kg Friction force was .002N Initial Speed 1m/s How far/ for how ling will the penny slide?

Question

I'm completely lost. How do I go about this?

Answer 1

The friction is putting the penny out of equillibrium and is classified as a retarding force (as it impedes forward motion).

The friction causes it to decelerate.

F=ma, a=F/m

force=.002N

m= .004kg

a=-0.5m/s^2 (negative because slowing down)

a=(vf-vi)/t, t=(vf-vi)/a

vf=0m/s (stopped)

vi= 1 m/s (given)

a=-0.5m/s^2

t=2s

Travels 2s

av velocity= dist/ time

av velocity= (vf+vi)/2

d/t=0.5(vf+vi)

d=0.5t(vf+vi)

d=0.5(2s)(0m/s+1m/s)=1m

travels 1s, goes 1m

Answer 2

First off, find the acceleration of the penny:

F = ma

0.002 = 0.004a

a = 0.5 m/s^2

Then use constant acceleration formula to find the distance:

v^2 = u^2 + 2as

1^2 = 0^2 + 2*0.5*s

1 = s

s = 1 m

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v = u + at

1 = 0 + 0.5*t

t = 2 s

So the penny will slide for 2 seconds, and for a distance of 1 metre.