Question

4) A ball with a mass of 0.15 kg has a velocity of 5 m/s. It strikes a wall perpendicularly and bounces off straight back with a velocity of 2 m/s. The ball underwent a change in momentum equal to (There is only one answer) (2p) A) 0.20 kg. m/s B) 1.20 kg. m/s C) 1.05 kg. m/s D) 6 kg. m/s E) 8.5 kg. m/s 5) A 2-kg mass moving with a velocity of 6 m/s collides elastically with a 4-kg mass moving in the opposite direction at 6 m/s. The 2-kg mass reverses direction after the collision and has a new velocity of 2 m/s. What is the new velocity of the 4-kg mass? (There is only one answer) (1) A) -1 m/s B) 1 m/s C) -2 m/s D) 2 m/s E) 1.2 m/s 6) During an inelastic collision between two balls, which of the following statements is correct? (There is only one answer) (2p) A) Both momentum and kinetic energy are conserved. B) Momentum is conversed, but kinetic energy is not conversed. C) Momentum is not conversed, but kinetic energy is conversed. D) Neither momentum nor kinetic energy is conversed. E) Momentum is sometimes conversed, but kinetic energy is always conversed. 7) Which of the following units is not used to measure torque? (There is only one an- swer) (1) A) slug .ft B) lb. ft C) N.m D) Dyne. cm

Answer 1

mals m=0 ug P hence ofron o Momentum is conserved , but kinetic Energy 4 0.15kg fritte velocity 4= 5 m/sec ofter collision velocity v= 2m/sec Change en momentum Ap- m (u+v) -0.15 (5+2) Ap = 1.05 kg m/sec hence option © 1.05 kg my oec es correct. for enplastic collision there there is loss hence kinetic Energy cloes not conserved but momentum es always conserved is not conexewed. of kinetic Energy