Download Newtons Laws Review Problems

Newtons Laws Review Problems
Newton’s First Law : Inertia
Read pages 44-54
1.
Explain inertia .
2.
Why do all objects eventually come to a stop if there is no force acting on them?
3.
If an elephant and a mouse both ran into you, which would have greater effect on you? Explain why.
4.
How doe the inertia of a 10 kg mass compare to the inertia of a 20 kg mass? Half as much
5.
Calculate the weight of an apple that has a mass of 0.65 kg. Fw = mg 6.37N
6.
What is the weight of a horse with a 340 kg mass? Fw = mg
7.
If a dog has a weight of 270 Newtons, what is the dog’s mass in kg? m = Fw/g 27.6 kg
8.
How does the tension in your arms compare when you hang from a clothesline with one arm versus two arms? With two it is half as much as the weight is
distributed by 2 arms instead of one.
9.
If a 100 Newton bucket is held in place by four ropes, what is the tension in each rope? 25 N
10. Why is a tightly strung rope suspended between two poles more likely to break than a rope that is hung with a slight sag?
Newton’s Second Law : F=ma
Read pages 59-64, 68-69
11. If a mass of 30 kg is pushed with equal force as a mass of 90 kg, how do the accelerations compare? 1/3 as much for the heavier man
12. A force of 200 Newtons is applied to a cart in order to get it moving. What force is needed to get a cart with twice the mass moving? 400 N
13. A shot-putter exerts a force of 140 N on a 4 kg shot. What is the acceleration on the shot? 35m/s2
14. An unbalanced force gives a 2 kg mass an acceleration of 5 m/s/s. What is the force applied to the object? 10 N
15. What force is needed to maintain an acceleration of 40 m/s/s for a 710 kg race car. The force of friction is 500 N. 28,900N (Consider the friction)
16.
A net force of 6,000 N causes a Chevy S-10 to accelerate at a rate of 4 m/s/s. What is the mass of the truck? 1500 kg
17.
What is the weight of the S-10 in pounds? In Newtons? 3300 lbs, 14,700 N
18.
How much force is needed to keep a 20 N stone from falling? 20 N
19.
A rubber ball weighs 49 N. What is the acceleration of the ball if an upward force of 69 N is applied? (Hint: find the net force, then the mass and acceleration)
4 m/s2
20.
What is the weight of a 50 kg stone? What force is needed to acceleration the stone upward at 3 m/s/s?
21. Two forces act concurrently on a 30 kg box. One force is 60 N east, while the second force is 80 N North. What is the resulting force on the box? (Find the
magnitude and the direction) 100N, 36 degrees
22. Calculate the acceleration on the box in #21. 2.2 m/s2
23. If the same box in problem #21 encounters a frictional force of 10 N, what is the resulting acceleration of the box? (Find net force then solve) 1.9 m/s2
24. A 24 kg crate is slid across the floor at a constant velocity. The force applied to the box is
53 N. Find the coefficient of friction between the floor and the crate. .22
25. What force is needed to slide a 25 kg chair across the floor at a constant velocity? The coefficient of friction between the chair and the floor is 0.30.
73.5 N
26.A museum curator moves a 145 kg aluminum sculpture across a steel platform. The coefficient of sliding friction is 0.47. What force must the curator apply to
maintain a constant velocity? 670 N
Newton’s Third Law : Action = Reaction (Forces come in pairs)
Read pages 74-80
24. While standing on the floor, name the pair of forces that are involved. Floor on foot, foot on floor
25. When you dive off of a boat, the boat moves backwards…why? You push off forward, opposite reaction to your push
26. When a gun is shot, the bullet shoots out one direction, while the gun recoils in the opposite direction. Compare the forces on the gun and bullet. Compare the
accelerations. Same force, but masses are different so different accelerations
27. A Cooper Mini and a Ford-250 truck have a head on collision. Which vehicle experiences the greater force on impact? Which vehicle experiences a greater
change in motion? Explain. Same force, but mini cooper accelerates more because of the mass difference