Equilibrium: As shown in the figure, a woman is straining to lift a large crate, but without success because it is too heavy. We denote the forces on the crate as follows: P is the magnitude of the upward force being exerted on the crate by the person, C is the magnitude of the vertical contact force on the crate by the floor, and W is the weight of the crate. How are the magnitudes of these forces related while the person is trying unsuccessfully to lift the crate?
A. P + C = W
B. P + C < W
C. P + C > W
D. P = C
Answer: A
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What will be an ideal response?
Given that all bodies in the solar system should have suffered equally from collisions during the period of early bombardment, if we find a body with relatively few craters on its surface we deduce that
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A spaceship leaves Earth at a steady forward speed of 70% the speed of light. How fast relative to the ship must the spaceship launch a shuttlecraft in the forward direction so that it will be moving away from Earth at 98.7% the speed of light?
A) 0.91c B) 0.97c C) 0.93c D) 0.99c E) 0.84c