for every action there is an equal and opposite reaction

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2 for every action there is an equal and opposite reaction

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7 Name Period Date Newton s Three Laws of Motion Study Guide 1. Gina is driving her car down the street. She has a teddy bear sitting on the back seat. A dog runs in front of Gina's car, so she quickly applies the brakes. The force of the brakes causes the car to stop, but the teddy bear continues to move forward until it hits the car's dashboard. The teddy bear did not stop at the same time as the car because of which Newton s Law of Motion? Newton s 1 st Law of Motion- an object (bear) will stay in motion until acted upon by an unbalanced force (dashboard) 2. Newton's _Third_ law of motion states that "For every action, there is an equal and opposite reaction." 3. Newton's First Law of Motion states that "An object at rest tends to stay at rest and an object in motion tends to stay in motion with the same speed and in the same direction unless acted upon by an unbalanced force." 4. Trevor is pushing two boxes across a sidewalk. Box A has a mass of 4 kg. Box B has a mass of 8 kg. According to Newton s Second Law of Motion, if Trevor applies the same amount of force to each box, A. box B will move twice the distance of box A. B. box A and box B will accelerate at the same rate. C. box A will accelerate at twice the rate of box B. D. box B will accelerate at twice the rate of box A. 5. When experimenting with the film canister rockets, the action was the downward push of the film canister on the desk. What was the reaction force? A. the upward force of the desk pushing on the film canister B. the downward force of the film canister s weight on the Earth C. there is no reaction force 6. When the net forces equal 0 N, they are balanced. 7. Unbalanced forces cause an object to start moving. (Hint: Newton s First Law of Motion) 8. What is the difference between mass and weight? Gravity; mass is the amount of matter that makes up an object; weight is the mass plus the amount of gravity pushing down on the object. 9. What is the force that opposes motion between two surfaces that are in contact? (friction or acceleration) friction 10. What is the net force of an object when you combine a force of 20 N north with a force of 15 N south? 5 N (north) 11. Albert Pujols (first baseman for the St. Louis Cardinals) and Mrs. Finley are traveling down the hallways of the school in teachers chairs at the same velocity. Which person has the most momentum? Why? Albert Pujols has the most momentum b/c he has more mass and more inertia.

8 Name Period Date 12. What is inertia and how is it related to Newton s First Law of Motion? Inertia is want to, it wants objects to keep going in a straight line at a constant speed; Newton s First Law states that objects will keep moving with inertia until acted upon by an unbalanced force. 13. What is the force necessary to accelerate an 85 kg object at a rate of 6.3 m/s²? (Use your FAM triangle.) F=a x m; F=85 x 6.3= N 14. What is the acceleration of a 1,456 kg truck if a force of 47,320 N is used to move the truck? (Use your FAM triangle.) a=f/m; a=47,320/1,456= 32.5 m/s² 15. Explain gravity (pg. 526). Gravity is a force of attraction between objects (due to their masses). 16. If a softball and a bowling ball are dropped from the same height at the same time, and there is no air resistance, which ball will hit the ground first? Why? (pg. 542) They would both hit the ground at the same time b/c the acceleration due to gravity is the same for all objects when there is no air resistance involved The equation a=f m represents Newton s second law of motion. Based on this equation, if balanced forces act on an object, what can be expected of the object s acceleration? 0 m/s 2 because it takes an unbalanced force to move or stop an object. 20. How does Newton s third law of motion explain why a swimmer moves forward in the water? The swimmer exerts a backward force on the water and the water exerts a forward force on the swimmer, pushing the swimmer forward.