Exam 3 Practice Problems

Exam 3 Practice Problems - If the fist is moving at 13 m/s...

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PH 1113 Exam III Extra Practice 1. A 14 kg object is pulled along a flat surface by an applied force of 30 N that acts at 25 degrees above the horizontal. The object moves a distance of 7 meters and the coefficient of friction is 0.15. A) What is the work done by the applied force? (190 J) B) What is the work done by friction? (-131 J) C) What is the work done by the normal force? (0 J) 2. A 10 kg cannonball is launched straight up from a catapult made of a spring (k=500 N/m) that is compressed 0.80m. A) How fast is the cannonball moving when it leaves the spring? (4.04 m/s) B) How high above its original position does is go? (1.63 m) 3. How long will it take a 170 kW motor to lift a 500 kg elevator a distance of 10 meters at a constant speed? (0.29 s) 4. A boxer’s fist (m=0.75 kg) is in contact with his opponent’s face for 0.03 seconds.
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Unformatted text preview: If the fist is moving at 13 m/s when contact is made and slows to 10 m/s during the punch, how much force is felt? (-75 N) 5. Ball 1 has a mass of 3 kg and is moving to the right at 6.00 m/s when it strikes and bounces off Ball 2 which has a mass of 5 kg and is moving at 4.00 m/s to the right. What is the velocity of the two balls after the collision? (3.5 m/s and 5.5 m/s) 6. A 50 gram bullet strikes an 18 kg block of wood sitting on a flat table and becomes embedded. The block (with the embedded bullet) slides 1.6 m along the table and there is a coefficient of static friction of 0.4 between the block and the table. What was the speed of the bullet just before impact? (995 m/s) 7. Where is the CM of the object below? (3.14 m from the left end)...
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