Answer:
<em>20 m/s in the same direction of the bus.</em>
Explanation:
<u>Relative Motion
</u>
Objects movement is always related to some reference. If you are moving at a constant speed, all the objects moving with you seem to be at rest from your reference, but they are moving at the same speed as you by an external observer.
If we are riding on a bus at 10 m/s and throw a ball which we see moving at 10 m/s in our same direction, then an external observer (called Ophelia) will see the ball moving at our speed plus the relative speed with respect to us, that is, at 20 m/s in the same direction of the bus.
The lithosphere includes the crust, and the mantle :)
Assuming constant acceleration, the goalie slows the ball from 18 m/s to rest in 0.035 s, so that the acceleration felt by the ball is
Their are two coefficients of friction, static and kinetic, regardless, they have basically the same formula:
u*N = F... aka
coefficient of friction*normal force = force of friction
Hope that helps!
