Section+3

=__//**Section 3- Newton's Second Law: Push or Pull**//__= toc

What Do You Think?
page 157 11/29/10

A force is a push or pull like gravity, man force, or wind. The same amount of force will affect a tennis bowl more than it would a bowling ball because a bowling ball has more mass.

Investigate
page 157 11/29/10

2a. It moves slow. 3a. it moves fast. b. They both move forward and are gaining speed. c. The smaller the bend the slower it moves and the slower it accelerates. The bigger the bend the faster it moves and the faster it accelerates. d. The greater the constant force on an object, the faster the acceleration. 4a. the object has less mass resulting in it being able to move faster with less force. It also accelerates quicker. 5a. the more mass results in moving slower and slower acceleration. It needs more force to move quick. b. When equal amounts of a constant force are used to push objects having different masses, the more massive object moves and accelerates slower. 6a. Smaller objects move fast with a large force and large objects move slow with a small force. 8a. it bent a small amount. 9a. it bends more. b. 1 represents a small force and 100 represent a large force. c. gravity.

Physics Talk
page 160 12/03/10

A constant force produces an acceleration. The more mass on the object, the less it accelerates. Newtons second low of motion is the acceleration of an object is directly proportional to the unbalanced fore acting on it and is inversely proportional to the object's mass. He wrote this in a book called, Principia. A=F/M. Where there's acceleration, there must be an unbalanced force. Using this you can also calculate the weight of an object. w=mg. An apple on a table is not accelerating because there is a force on both sides of it.

Checking Up
page 167 12/03/10

1. The acceleration of an object is directly proportional to an unbalanced for. 2. It slows it down 3. The mass is 3.06 kg because w=mg and the acceleration due to gravity would be 9.8 m/s. 4. your weight and mass would increase.

Physics To Go
page 171 12/03/10

1. f= 350N m= 80 kg a= 10 m/s m= 80 kg a= -15 m/s f= -3000 2a. long jumper and the shot put. They are not coincidences, it is because the gravity is what is pushing them down. b. For a force to be negative it would mean that it is giving up on it so the acceleration could also be negative. c.Yes, the force should be shown as negative 3. 140 m/s/s 4. .8N 5. a. An object in motion will stay in motion so it is harder to stop it. b. The more mass the more force needed. 6. .98N 7a. 657n 7b. 67kg 8. Both are applying equal forces to the rope each pulling in a different directions but the more force applied to one side that side will win. 10. unbalanced force is 10 N 11. 800 N 12. .2m/s^2 15. 125.4 N