A uniform diving board, 12 meters long and 20 kg in mass, is hinged at P, which is 5 meters from the edge of the platform. An 80
kg diver is standing at the other end of the board. hinge 1. The force exerted by the hinge on the board will be very nearly a) 1000 N upward b) 1080 N upward c) 1080 N downward d) 1160 N upward e) 1160 N downward 2. The normal force on the board at the edge of the platform will be a) 2160 N b) 1000N c) 200 N d) 160 N e) 60 N
1 answer:
You might be interested in
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).