A 2000 kg car slams on the brakes and slows down at a rate of -10 m/s2. How much force are the brakes applying?
1 answer:
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Answer:
E. Zero Maximum
Explanation:
At the point of maximum displacement, the speed is zero while the restoring force is maximum. In fact:
- The restoring force is given by , where k is the spring constant and x is the displacement - at the point of maximum displacement, x is maximum, so F is maximum as well
- the total energy of the system is sum of kinetic energy and elastic potential energy:
where m is the mass of the system and v is the speed. Since E (the total energy) is constant due to the law of conservation of energy, we have that when K increases, U decreases, and viceversa. As a result, when x increases, v decreases, and viceversa. At the point of maximum displacement, x is maximum, so v will have its minimum value (which is zero, since the system is changing direction of motion).