Question

. If a disk rolls smoothly across a floor, what is the velocity of the point that is in contact with the floor? a) twice the velocity of the center of the disk b) equal to the velocity of the center of the disk c) zero 2. Stress is proportional to strain means that a) stress = constant x strain. b) stress (constant 1) X strain+ constant 2. stress Constant strain d) stress= constant 1 strain constant 2 e) Stress x strain = constant. 3. Angie says that an object is in equilibrium if the net torques about the center of mass is zero. Robbie says that an object is in equilibrium if the sum of external forces is zero. Which one, if either, is correct? a) Both are correct: an object is in equilibrium if either condition holds. b) Neither is correct: both conditions must hold simultaneously c) Neither is correct: the net external force and the net external torque about any axis must be zero. Neither is correct: an object is in equilibrium only if its velocity is zero in all coordinate systems. Both are correct: if the sum of the external forces is zero, the net torque about any axis is automatically zero, and vice versa. d) e) 4. A moon orbits a planet along an elliptical path. Which describes the location of the planet within the ellipse? a) must be at the center b) an be anywhere along the major axis c) can be anywhere along the minor axis d) must be at a focus 5. The escaping speed of a satellite from the earth depends on its mass a) True b) False

Answer 1