7. A 0.145 kg baseball pitched at 35m/s is hit on a horizontal line drive straight back toward the pitcher at 50m/s. If the contact time between the bat and ball is 5times 10^-3 seconds, calculate the force between the ball and bat during contact.

Here's how to calculate the force between the bat and ball:<br /><br />1. **Calculate the change in velocity:** The ball's initial velocity is -35 m/s (negative because it's moving towards the batter). Its final velocity is 50 m/s. The change in velocity (Δv) is:<br /><br /> Δv = Final velocity - Initial velocity = 50 m/s - (-35 m/s) = 85 m/s<br /><br />2. **Calculate the acceleration:** Acceleration (a) is the change in velocity divided by the time interval (t):<br /><br /> a = Δv / t = 85 m/s / (5 x 10⁻³ s) = 17,000 m/s²<br /><br />3. **Calculate the force:** Force (F) is the product of mass (m) and acceleration (a):<br /><br /> F = m * a = 0.145 kg * 17,000 m/s² = 2465 N<br /><br />Therefore, the force between the ball and bat during contact is $\boxed{2465 N}$.<br />