Question

question #5: a person with a weight of 225 lbs is standing on a scale. what force is the scale exerting on the person? options: 225 lbs down, 225 lbs up, 450 lbs up, 0 lbs up. question #6: a truck has a momentum of 52,000 kg·m/s. it crashes into a car at rest. after the collision, the momentum of the truck and the car should equal. options: more than 52,000 kg·m/s, 52,000 kg·m/s, less than 52,000 kg·m/s, there is not enough information to know the total momentum.

Explanation:

Question #5

Step1: Recall Newton's third - law

The force the scale exerts on the person is equal to the person's weight. The person's weight is given as 225 lbs. Since the person is standing still on the scale, the normal force (force exerted by the scale on the person) balances the weight.

Step1: Apply the law of conservation of momentum

In an isolated system (neglecting external forces during the short - time collision), the total initial momentum of the system (truck + car) is equal to the total final momentum of the system. The initial momentum of the car is 0 (at rest), and the initial momentum of the truck is 52,000 kg m/s. So the total initial momentum of the system is 52,000 kg m/s, and the total final momentum of the truck - car system should also be 52,000 kg m/s.

Answer:

225 lbs up

Question #6