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Published byJanice Scott Modified over 9 years ago
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Fall Final Review WKS: WORD PROBLEMS Part II
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1. A car travels at a constant speed of 15 m/s for 10 seconds. How far did it go?
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2. How much time will it take to walk 100 meters at a constant speed of 2 m/s?
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3. You drop an object off the top of a 75 meter tall building. It falls freely and hits the ground 7 seconds later. What is the average speed of the object as it fell?
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4. You drop a rock off the top of a tall cliff. How fast is it traveling 3 seconds later?
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You are asked to calculate the final velocity (v) Initial velocity: V 0 = 0 since you “dropped” the rock
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5. You drop a 4.0 kg rock from a height of 20.0 meters above the ground. How long will it take to hit the ground?
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In a free fall problem the mass does not change the acceleration of an object when there is no air resistance
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6. According to the figure below, what is the acceleration of the block?
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First you need to calculate the net force (20 -10 =10)
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7. A net force of 10 Newtons is used to push a car about 25 yds. The car’s acceleration is 1.0 m/s2. What is the mass of the car?
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8. You kick a 0.5 kg stationary ball with a force of 20 Newtons. What is the force on your foot?
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Newton’s Third Law states that the forces are equal and opposite in direction Force would be 20N
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9. If you have a weight of -850 Newtons, and are standing on the ground. What is the force that the Earth is pushing back up on you?
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850 N -850 N Remember that weight (force of gravity) is pointed downward. We can represent down with a (-) sign
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10. What happens to the gravitational attraction (the force) between two objects when the distance between them increases? decreases?
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Newton’s Law of Universal Gravitation tells us the relationship of distance and mass on the gravitational force Distance is on the bottom so it is inversely proportional-distance gets greater, force gets smaller When distance decreases, force increases
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11. When an object is moving in uniform circular motion, which way is it accelerating?
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Both acceleration and centripetal force are pointed to the center of the circle
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12. Each of the 3 objects below moves with a velocity of 1m/s. What is the total kinetic energy of the system?
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To calculate total kinetic energy you need to add up the masses of the 3 objects.
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13. What is the kinetic energy of an object with a mass of 5 kg traveling at a speed of 10 meters/second? Assume no other forces act upon the object.
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14. You lift a heavy rock with a mass of 15 kg to a height of 5.0 meters above the ground. What is the potential energy given to the rock?
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15. A 1.5 kg rock falls to the ground off the top of a 25 meter tall cliff. What is the Kinetic energy of the rock right before it hits the ground?
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We do not have velocity to use in equation for KE. Calculate the PE knowing it will all be transformed into KE
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16. A 3.5 kg object is moving with a velocity of 2.0 m/s. What is its momentum?
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17. The diagram below represents an inelastic collision between two blocks on a frictionless air track. After the collision the two objects “stick” together. What is the mass of the second box?
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Calculate the total momentum of both boxes before the collision. It will have the same total momentum after as well
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17. The diagram below represents an inelastic collision between two blocks on a frictionless air track. After the collision the two objects “stick” together. What is the mass of the second box? Since the total momentum before = 400 Total momentum after = 400
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18. When the two objects of different mass collide and couple together, what will be their resultant velocity?
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Calculate the total momentum of both boxes before the collision. It will have the same total momentum after as well
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18. When the two objects of different mass collide and couple together, what will be their resultant velocity? Since the total momentum before = 100 Total momentum after = 100
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