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Explain your reasoning. Q4.27. Why is it incorrect to say that 1.0 kg equals 2.21b? Q4.l8. A horse is hitched to a wagon. Since the wagon pulls back on the horse just as hard as the horse pulls on the wagon, why does the wagon notremain in equilibrium, no matter how hard the horse pulls? Q4.l8. True or false? You exert a push P on an o~ect and it pushes back on you with a force F. If the object is moving at constant velocity, then F is equal to P, but if the o~ect is being accelerated, then P must be greater than F. (14.30. A large truck and a small compact car have a head-on colli-sion. During the collision, the truck exerts a force F Ton C on the car, and the car exerts a force FConT on the truck. Which force has the larger magnitude, or are they the same? Does your answer depend on how fast each vehicle was moving before the collision? Why or why not? (14.31. When a car comes to a stop on a level highway, what force causes it to slow down? When the car increases its speed on the same highway, what force causes it to speed up? Explain. Exercises 131 (14.32. A small compact car is pushing a large van that has broken down, and they travel along the road with equal velocities and accelerations. While the car is speeding up, is the force it exerts on the van larger than, smaller than, or the same magnitude as the force the van exerts on it? Which object, the car or the van, has the larger net force on it, or are the net forces the same? Explain. (14.33. Consider a tug-()f-war between two people who pull in opposite directions on the ends of a rope. By Newton's third law, the force thatA exerts on B is just as great as the force that B exerts on A. So what determines who wins? (Hint: Draw a free-body dia-gram showing all the forces that act on each person.) (14.34. On the moon, g = 1.62 mfS'. If a 2-kg brick drops on your foot from a height of 2 m, will this hurt more, or less, or the same if it happens on the moon instead of on the earth? Explain. If a 2-kg brick is thrown and hits you when it is moving horizontally at 6 mfs, will this hurt more, less, or the same if it happens on the moon instead of on the earth? Explain. (On the moon, assume that you are inside a pressurized structure, so you are not wearing a spacesuit.) (14.35. A manual for student pilots contains the following passage: "When an airplane flies at a steady altitude, neither climbing nor descending, the upward lift force from the wings equals the air-plane's weight. When the airplane is climbing at a steady rate, the upward lift is greater than the weight; when the aitplane is descending at a steady rate, the upward lift is less than the weight." Are these statements correct? Explain. (14.36. If your hands are wet and no towel is handy, you can remove some of the excess water by shaking them. Why does this get rid of the water? (14.37. If you are squatting down (such as when you are examin-ing the books on the bottom shelf in a library or bookstore) and suddenly get up, you can temporarily feel light-headed. What do Newton's laws of motion have to say about why this happens?