Question

39. What happens to a spaceship flying through space with no engines and no external forces acting on the spaceship? A. It gradually slows down. B. It gradually speeds up. C. Its speed doesn't change. D. We have no idea what happens to the spaceship. 40. A 10-N horizontal force is applied to a box that weighs 24 N. If the box does not move on the horizontal surface (m.- 0.5), what is the force of friction? A. 5 N B. 10N C. 12 N D. 24 N 41. A mosquito and a truck have a head-on collision. Splat! Which has a larger change of momentum? A. The mosquito. B. The truck. They have the same change of momentum. Can't say without knowing their initial velocities C. 42. You awake in the night to find that your living room is on fire. Your one chance to save yourself is to throw something that will hit the back of your bedroom door and close it, giving you a few seconds to escape out the window. You happen to have both a sticky ball of clay and a super-bouncy Superball next to your bed, both the same size and same mass. You've only time to throw one. Which will it be? Your life depends on making the right choice! A. Throw the Superball. B. Throw the ball of clay C. It doesn't matter. Throw either. 43. If you were to tighten a bolt (requiring a torque of 10 Nm) with a wrench, what minimum force would you need to apply at the end of a 0.350 m long wrench handle? c) 15.4 N d) 6.50 N a) 28.6 N b) 3.50 N

Answer 1

39. If we don't consider gravitational attraction due to another planets or can be ignored if they are too far away. Then there will no change in the velocity. So (c)

40. As the box does not move then the frictional force will be equal to the force applied. So (B) 10 N

41. As the mass of truck is very very larger than the mass of mosquito , so the change in momentum for mosquito will be larger. So (A)

42. As the super  ball will reflect back so less amount of momentum will be transferred. While for clay ball the momentum transferred will be larger as it will stick. So (B)

43. Torque = distance ×Force

so force = torque / distance = 10/0.35 = 28.57