When a soccer ball is kicked toward a player and the player deflects the ball by "heading" it, the acceleration of the head during the collision can be significant. The figure gives the measured acceleration a(t) of a soccer player's head for a bare head and a helmeted head, starting from rest. At time t = 7.0 ms, what is the difference in the speed acquired by the bare head and the speed acquired by the helmeted head? 200 Bare È 100 Helmet 2 t (ms) 4 6 Number i Units

1 4. The plot below shows the velocity of a hockey puck as a function of time. The puck starts at time t=0 at position x-3 m in the positive direction. All quantities are measured in SI units (meters and seconds). v (m/s) -1 1 2 4 t(s) a) Draw sketches of corresponding position versus time and acceleration versus time for the puck. The time axis is identical for all 3 graphs/sketches (this one, position, acceleration graphs) At time t-4s, what is the puck's position? At time t-3s, what is the puck's acceleration?

Tired, you walk from your house to a local coffee shop to get an espresso. You average a speed of 2.4 m/s on your way there. After your espresso, you decide to run directly back to your starting point with an average speed of 5.6 m/s. Assume you spend 4 minutes at the coffee shop. If your average speed for this entire trip is 1.9 m/s, what is the distance between your house and the coffee shop?

A tennis ball is thrown straight upward with an initial speed of 15 m/s. What is the speed of the ball 1.1 seconds later?