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Unformatted text preview: homework 07 RAHMAN, TARIQUE Due: Feb 15 2008, 3:00 am 1 Question 1, chap 5, sect 1. part 1 of 1 10 points An elevator is being lifted up an el- evator shaft at a constant speed by a steel cable as shown in the figure be- low. All frictional effects are negligible. steel cable Elevator going up at constant speed In this situation, forces on the elevator are such that 1. the upward force by the cable is smaller than the downward force of gravity. 2. the upward force by the cable is greater than the downward force of gravity. 3. the upward force by the cable is equal to the downward force of gravity. 4. the upward force by the cable is greater than the sum of the downward force of gravity and a downward force due to the air. 5. None of these. (The elevator goes up because the cable is being shortened, not be- cause an upward force is exerted on the eleva- tor by the cable.) Question 2, chap 5, sect 1. part 1 of 1 10 points A space probe is carried by a rocket into outer space where it continues to move on its own in a straight line. What keeps the probe moving? 1. Nothing keeps the probe moving. The probe will eventually stop. 2. The gravitation forces from different stars and planets keep the probe moving. 3. There must be a propeller that keeps the probe moving. 4. None of the above 5. Nothing specific keeps the probe moving. In the absence of forces it would continue moving in a straight line....
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