To understand the relationship between force, impulse, and momentum. The effect of a net force ΣF⃗ acting on an object is related both to the force and to the total time the force acts on the object. The physical quantity impulse J⃗ is a measure of both these effects. For a constant net force, the impulse is given by J⃗ =F⃗ Δt. The impulse is a vector pointing in the same direction as the force vector. The units of J⃗ are N⋅s or kg⋅m/s. Recall that when a net force acts on an object, the object will accelerate, causing a change in its velocity. Hence the object's momentum (p⃗ =mv⃗ ) will also change. The impulse-momentum theorem describes the effect that an impulse has on an object's motion: Δp⃗ =J⃗ =F⃗ Δt. So the change in momentum of an object equals the net impulse, that is, the net force multiplied by the time over which the force acts. A given change in momentum can result from a large force over a short time or a smaller force over a longer time.
Now assume that the pitcher in Part D throws a 0.145 kg baseball parallel to the ground with a speed of 20.0 m/s in the -x direction. The batter then hits the ball so it goes directly back to the pitcher along the same straight line. What is the ball's x-component of velocity just after leaving the bat if the bat applies an impulse of +6.9N⋅s to the baseball? Enter your answer numerically in meters per second using two significant figures.