4. A 4-kg block slides on a frictionless surface at 40 m/s toward a 6-kg block (with a massless sponge attached) initially at rest. The force that the 4-kg block exerts on the 6-kg block is plotted below. Vo=40m 4 kg 6 kg -+ 400 300 F(N) 200 bol some rea mid collis 100 5 - 8 a. What is the total impulse of the 4-kg block on the 6-kg block? b. Sketch the plot of the force of the 6-kg block on the 4-kg block (vs. time). c. Find the speed of the 6-kg block after the collision. d. Find the speed of the 4-kg block after the collision. How much energy is lost or gained during the collision