![]() So, in this case, the upper string will break. One is the downward weight attached and the other is the force applied. (A) The upper string is exposed to two forces. What is the net force exerted on the skier, assuming his acceleration is constant? When the wheels push against the ground, the ground is able to exert a reaction force on the car to move it.Ī 92-kg water skier floating in a lake is pulled from rest to a speed of 12 m/s in a distance of 25 m. The drag racer needs an engine to turn the wheels, which in turn makes them push against the ground. Why, then, does it need an engine? Explain. What average force acted on the ball during this time?Ī drag-racing car accelerates forward because of the force exerted on it by the road. A 0.53-kg billiard ball initially at rest is given a speed of 12 m/s during a time interval of 4.0 ms.What happens when this force is equal in magnitude to her weight? Explain. As she slides faster and faster she tightens her grip, increasing the force exerted on her by the rope. If the sled has a mass of 7.4 kg, what is the mass of your little sister?Ī young girl slides down a rope. When you exert a constant horizontal force of 120 N, the sled has an acceleration of 2.5 m/s2. You are pulling your little sister on her sled across an icy (fric-tionless) surface. The water drops fall away from the body when the position of the dog’s body is changed rapidly. When a dog shakes its body, the water remains at rest because of inertia. If the cart starts at rest, how far does it move in 2.50 s? In a grocery store, you push a 12.3-kg shopping cart with a force of 10.1 N. ![]() However when you are viewed from other planets, you are not at rest relative to the vantage point of the other planets. You are not at absolute rest, you are at rest with respect to the other objects in your surroundings. Can you conclude, therefore, that you are at rest? Explain. Tf the astronaut exerts an upward force of 46.2 N on the rock, what is its acceleration?Īs you read this, you arc most likely sitting quietly in a chair. The rock has a mass of 5.00 kg, and on this particular planet its weight is 40.0 N. On a planet far, far away, an astronaut picks up a rock. Using Newton’s laws of motion, explain how this stunt works. You’ve probably seen pictures of someone pulling a tablecloth out from under glasses, plates, and silverware set out for a formal dinner. In terms of T, how long does it take for the object to accelerate from rest to a speed v now? Suppose the mass of the object is doubled, and the magnitude of the force acting on it is quadrupled. After a force of magnitude F acts on it for a time T, the object has a speed v. Thus, because of inertia, the body moves toward the front of the car.ĬE An object of mass m is initially at rest. The body, however, keeps moving at the same speed. When the brakes are applied, the car slows down. As a result, your body moves toward the front of the car. Mastering Physics Solutions Chapter 5 Newton’s Laws Of Motionĭriving down the road, you hit the brakes suddenly.
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