1)- An object is being acted upon by three forces and moves with a constant velocity. One force is 60.0 N along x-axis, the second is 75.0 N along the y-axis. What is the magnitude of the third force? A- 15.0 N B- 96.0 N C- 48.0 N D- 20 N ____________________________________________________________ 2)- A chatcher stops a ball traveling at 40 m/s in a distance of 20 cm and feels a force of 600 N against hid glove. What is the mass of the ball? A- 0.30 kg B- 0.25 kg C- 0.15 D- 0.20 kg ____________________________________________________________ 3)- How much energy is needed to charge the speed of a 1600 kg sport utility vehicle from 15.0 m/s to 40 m/s ? A- 1.10 M B- 40.0 kJ C- 1.10 MJ D- 0.960 MJ ____________________________________________________________ * Now i have 2 questions i just want to make sure about the answers. 4)- How much work is required to stretch a spring 25.2 cm if its force constant is 12.3 N/m ? A- 1.05 J B- 3.10 J C- 0.391 J D- 0.381 J i used the law: W = F x D, F = 12.3 N/m, D = 25.2 cm = 0.252 m, W = 12.3 x 0.252 = 3.09 J so the answer is B. Correct? ____________________________________________________________ 5)- John's mass is half the mass of Kim. They both start walking and John moves twice as fast as Kim. What is the ratio of the kinetic energy of Kim to the kinetic energy of John? A- 1/8 B- 1 C- 2 D- 1/2 now if John's mass is 1 then Kim's mass is 2, and if John's velocity if 2 the Kim's velocity is 1 John: Ek = 0.5 x 1 x 4 = 2 Kim: Ek = 0.5 x 2 x 1 = 1 so the answer is D. Correct?