Review for Dynamics Test

Review for Dynamics Test

NOTE: You are responsible for everything you did with me! Even if it isn’t listed here by accident!

Topics:

1. What is a force?2. Contact vs non-contact forces

3. Types of Forces (normal force)4. Inertia

5. Weight vs Mass, weight/mass on different planets or places on Earth

6. Friction – static vs kinetic, coefficient of friction, what does friction depend on?

7. Net force8. Free Body Diagrams, balanced forces

9. Newton’s Three Laws

10. Systems of Masses problems (for pulleys and for boxes that are pushed together)

11. Word Problems involving both kinematics and dynamics

12. Inertial and non-inertial frames of reference

Word Problems:

Non-Mathematical Questions (ie, no numbers just the big ideas)

Give an example of an inertial frame of reference.
Give an example of a non-inertial frame of reference.
Newton’s Laws apply in ______frames of reference.

HINT: This is a system of masses! Newton’s 3rd law applies…

Systems of Masses

1. A1.0 kg box on a horizontal frictionless surface is accelerated by attaching a 1.5 kg mass hanging over a pulley. What is the acceleration of the box?

{5.9 m/s2}

2. Two masses of 1.5 kg and 2.0kg are hung on a frictionless pulley. What is the acceleration of each mass?

{1.4m/s2}

3. A 3.5 kg box on a horizontal surface is accelerated by attaching a 8.2 kg mass hanging over a pulley. If the coefficient of friction between the box and surface is 0.335, find the acceleration of each mass.

{5.9m/s2}

Newton’s 3rd Law

1)According to legend, a horse learned Newton’s laws. When told to pull a cart, he refused, saying that if he pulled the cart forward, according to Newton’s Third Law there would be an equal force backwards. Thus, there would be balanced forces and, according to Newton’s Second Law, the cart would not accelerate. How would you reason with this rather weird horse?

2)When you drop a 0.40 kg apple, Earth exerts a force on it that causes it to accelerate at 9.8 m/s2. According to Newton’s third law, the apple must exert an equal and opposite force on Earth. If the mass of the Earth is 5.98×1024 kg, what is the Earth’s acceleration?

3)A person exerts an upward force of 40 N to hold onto a bag of groceries. Describe the "reaction" force (Newton's third law) by stating (a) its magnitude, (b) its direction, (c) on what body it is exerted, and (d) by what body it is exerted.

4)According to Newton's third law, each team in a tug-of-war pulls with equal force on the other team. What, then, determines which team will win?

If two people each standing on a scooter board push off of each other what happens (relate to Newton's Third Law)?

7. If a person standing on a scooter board pushes off of a wall, what happens? Can this situation be explained in terms of Newton's Third Law (action-reaction)?

How is shooting a shotgun related to Newton's Third Law?

Friction:

What affects friction?