Online Experiment 7 Momentum & Impulse – Online Version

Online Experiment 7: Momentum and Impulse – Laboratory Report Pre-Lab Questions A. (5 pts) In which type of collisions is momentum conserved? Why? For both types of collisions, momentum is conserved. According to the law of conservation of momentum, the total momentum before the collision equals the total momentum after the collision as long as no external forces act on the system. In both elastic and inelastic collisions in this experiment, there is no external forces affecting the systems and thus momentum is conserved. B. (5 pts) In which type of collisions is kinetic energy conserved? How can it be “lost”? Kinetic energy is conserved in the case of elastic collision. This is because during the collisions object bounce off each other without deformation or generation of heat, sound or any other form of energy. This is as opposed to inelastic collisions where objects get deformed during collisions. C. (5 pts) Imagine two objects of equal mass moving toward each other with equal and opposite velocities. Does the momentum cancel to zero? Does the kinetic energy cancel to zero? Yes, the momentum cancel to zero because momentum is a vector quantity. When the velocities are equal in magnitude but opposite in direction, the total momentum of the system is zero. Total momentum = m(+v) + m(-v) = mv - mv = 0 The kinetic energy, on the other hand, does not cancel to zero because kinetic energy is a scalar quantity that depends on the square of velocity. The negative sign in velocity is eliminated when squared, so the kinetic energies add up rather than cancel. Total kinetic energy = ½m(+v)² + ½m(-v)² = ½mv² + ½mv² = mv² D. (5 pts) Give several examples of an impulse. How are impulse and momentum related? Examples of impulse include: soccer player hitting a ball, stricking a ball with tennis racket, car airbag deploying, hitting baseball ball with a bat, hitting a golf ball, and boxer’s glove hitting a punching bag. Impulse (I) is as the product of force and the time interval over which it acts: I = F·Δt. Impulse is directly related to momentum through Newton's Second Law: I = F·Δt = Δp. This implies that impulse equals the change in momentum. When a force acts on an object over a time interval, the impulse delivered to the object is equal to the change in the object's momentum. This relationship is useful in analyzing situations where large forces act over very short time periods e.g. in collisions. Inelastic Collisions: Data and Analysis (10 pts) Table 1 Trial m1 [kg] v1i [m/s] m2 [kg] v2i [m/s] KEi [J] vf [m/s] KEf [J] 1 0.5 0.2 0.5 0 0.01 0.1 0.005 2 0.65 0.7 0.6 0.1 0.0905 0.315 0.0647 3 0.8 0.3 0.4 0.9 0.44 0.267 0.0427 4 1 0.7 0.5 1 0.165 0.467 0.163 (10 pts) Description & Observations of simulation for Trial 1 In Trial 1 of the inelastic collision simulation, I observed that the red wagon (m₁) was initially ...