## anonymous 3 years ago A soccer ball is kicked in space, where we assume there is no friction or other forces acting on the ball, at 13 m/s. How much force is needed to keep the ball moving?

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1. anonymous

$S=\frac{1}{2}at^2+vt+s_0$ $S=\frac{1}{2}at^2+vt$ $V=at+V_0$ assuming the ball was sitting in space at rest $V=at=13$ $\frac{13}{a}=t$

2. anonymous

None. since there is no other forces impeding its movement, and since it is moving with uniform velocity, then it will, by Newton's first law, continue to move.

3. anonymous

I thought the question asked what was the force upon the ball -.-

4. anonymous

yes. the question asks what is the force on the ball that keeps it moving.

5. anonymous

In the case of the force required to get the ball to 13 m/s, it also depends on how long you exert the force and the mass of the ball. If you apply 10000N but only for a microsecond, you won't gain much velocity. The relation between force and acceleration is $F = m*a = m * \frac{ \Delta v }{ \Delta t }$ Then, to gain a speed of 13 m/s, the relation is: $13 = \frac{ F * \Delta t }{ m }$