For each of the statements below State whether it is True or

For each of the statements below. State whether it is True or False. If you chose F, explain why the statement is false & try to provide a counter example. If you chose T, justify/prove/explain why you believe the statement is true. Two cars, Car A and Car B, crash into each other. During this collision, it is necessarily true that: vector F_AB = - vector F_BA (i.e. the force that B exerts on A =the neg of the force that A exerts on B.) W_AB = -W_BA vector J_AB = - vector J_BA Total KE (of both cars) before the collision total KE after the collision. Total linear momentum before the collision = total linear momentum after the collision. vector P_A, before = -vector P_A, after vector P_A, before= vector_B, after Sum of the velocities before the collision = sum of the velocities after the collision PART 2: SUPER PENDULUM REVISITED A simple pendulum is constructed by attaching a bob of mass M to a string of length 2m. The bob is placed at equilibrium and given an initial velocity of 10 m/s. The pendulum swings upwards, slowing down as it swings. At some moment, its speed is 8 m/s. Compute the kinetic energy of the bob at this moment. Compute the gravitational potential energy energy of the bob at this point. Compute the vertical height of the bob at this moment. Compute the angle that the string forms with the vertical at this moment. Compute the centripetal acceleration that the bob is experiencing at this moment. Draw an FBD of the bob at the this moment. Apply Newton\'s Second Law to both axes. Compute the tension on the string at this moment. Compute the tangential acceleration at this moment. The pendulum swings all the way up to the TOP of its circular path. Find the bob\'s speed at this moment (when the bob is at the top of its path). Find the centripetal a that the bob has at this moment if it\'s still going in a circle. Draw an FBD of the bob at this moment. Assume that the bob is still going in a circle. Find the tension on the string at this instant. If tension suddenly disappeared (i.e. if the string broke), what would happen to the bob over the next second. Explain & draw in as much detail as possible the path the bob would take if the string broke.

Solution

A. when two cars collide each ohter the force exerted on A is opposite to B. Hence true. B. weight of force AB is equal to weigh of force BA not opposite so B is false. C is true. D is false because the total kinetic energy will be conserved