QUICK REVIEW (MONDAY, 9/30/13) Exam #3

Review Question #1 Joe pushes a 2-kg ball with a force of 10 newtons, Sally pushes the same ball with twice the force. How does the acceleration of Sally’s push compare to that of Joe’s push? a) The acceleration is ½ as much b) The acceleration is the same c) The acceleration is twice as much Acceleration = force/mass a=F/m If force doubles (and mass stays the same), what happens to acceleration?

Review Question #2 Joe pushes the same 2-kg ball again with 10 newtons of force. This time Sally pushes a 4-kg ball also with 10 newtons of force. How does the acceleration of Sally’s push compare to Joe’s push? a) The acceleration is ½ as much b) The acceleration is the same c) The acceleration is twice as much Acceleration = force/mass a=F/m If mass doubles (and force stays the same), what happens to acceleration?

Review Questions #3 & #4 In question #2, why was the acceleration of the balls different?  The more massive ball had more inertia  The less massive ball had more inertia  The force on the balls was different We used the equation to answer #1 & #2, but this question is conceptual What is the property of matter that resists a change in motion? What does that property depend on?

Review Question #5 Newton’s 1 st Law is often called a) The Law of Forces b) The Law of Motion c) The Law of Inertia Newton’s 3 Laws are all collectively known as Newton’s Laws of Motion There is no “Law of Forces”

Review Question #6 Newton’s 2 nd Law deals with the relationships between a) Mass and Weight b) Acceleration, Speed, and Distance c) Force, Mass, and Acceleration The equation that we use for the 2 nd Law is : F=m x a

Questions 7-9 g=9.8 m/s 2 F=m x a Weight is a force, with “g” used for “a” Let’s use that A freely falling object has an acceleration of ______________. The weight of an object is given by what equation?___________ What is the weight (in newtons) of a 10-kg mass?_______________ A = g = 9.8 m/s 2 W = mass x g W = 10 kg x 9.8 m/s 2 Weight = 98 N

What is acceleration at 6 N of force? What is the mass of this object? From this chart, we can determine force, acceleration and mass. Remember the equations: F = M x A M = F / A A = F / M Review Questions #10, #11 & #12 2 m/s 2 Read from the graph m = (6 N ) / (2 m/s 2 )m = 3 kg

Review Questions #13, #14 & #15 What is the force on a 3.5 kg object that is accelerated at 2 m/s 2 ? A force of 300 newtons applied to a rocket accelerates it to 600 m/s 2. What is the rocket’s mass? A force of 60 newtons on a ball with a mass of 3 kilograms has what acceleration?

Review Questions #16, #17 & #18 A mass of 0.5 kg is thrown with an acceleration of 9.8 m/s 2. What force was required? A toy car accelerates at 2.5 m/s 2. The force on the car was 1.25 N? What was the toy car’s mass? If a 4-kg cannonball is fired with a force of 6000 newtons, what is its acceleration?