In: Physics
Correct answer is given, please explain why for each.
Concept Question 1 – A rock is thrown straight up from the surface of the earth. Ignoring air resistance, which of the following statements is correct as the rock moves upward? a) The total energy of the rock increases. b) Both the kinetic energy and the gravitational potential energy of the rock remain the same. c) Both the gravitational potential energy and the total energy of the rock increase. d) Both the kinetic energy and the total energy of the rock decrease. e) The kinetic energy of the rock decreases and the gravitational potential energy of the rock increases.
E is correct.
Concept Question 2 – A stationary bomb explodes in space breaking into several fragments. The net external force on the bomb at the time of the explosion is zero. Which statement is correct? a) The total kinetic energy is conserved. b) The sum of the kinetic energies of all the fragments is zero. c) The vector sum of the linear momenta of the fragments is zero. d) The velocity of any one fragment must be equal to the velocity of any other fragment. e) The speed of any one fragment must be equal to the speed of any other fragment.
C is correct
Concept Question 3 – Complete the statement: A collision is elastic if a) the total final momentum of the system is zero. b) the objects stick together. c) the final kinetic energy of the system is zero. d) the total kinetic energy of the system is conserved. e) the total momentum of the system is conserved.
D is correct.