In each situation you will mark the directions and magnitudes of each force according to
Newton’s 3rd law. You will not have to identify the Net Force in this exercise.
Let’s start with an example.
A ball is rolling down a hill, on Earth. What are the forces involved in this situation if friction is
negligible?
First lets identify what forces could be present in this situation.
We have a ball with nothing pushing it, meaning that only gravity can be acting on the ball
directly to cause motion.
The ball is not falling through the ground which means that there must be some force given by
the ground to counteract the gravitational force.
After identifying what our forces must be we should put variables to it for ease of use.
Gravitational Force = Fg
Normal Force = Fn
With the variables known if we knew the values we could plug them in at this point, but since we
do not we can only label our picture with our variables. With their given directions. Remember
the size of your arrow corresponds to the magnitude of the force.
Made using the google doc drawing tool, when you click on the image it will allow you to edit the
image to make your solution.
Problem Number 1:
A box sits on the floor in a classroom on Earth. This box weighs 90N.
Click on image, hit edit, and then adjust arrows to match the forces, use textbox for labeling.
Problem Number 2:
A woman pushes a box across his floor. The floor attributes a negligible frictional force. The
man must put in double the box’s weight (45N) when pushing the box.
Click on image, hit edit, and then adjust arrows to match the forces, use textbox for labelling.
Problem Number 3:
A car rolls forward on the road exerting 3 kN of force doing so. It weighs double that value on
the planet it is on.
Click on image, hit edit, and then adjust arrows to match the forces, use textbox for labelling.
Challenge Problem Number 4:
A ball falling through the air straight down in freefall. There is no air resistance on the ball.
Click on image, hit edit, and then adjust arrows to match the forces, use textbox for labelling.
Challenge Problem Number 5:
This jeep travels up a hill. The hill itself has no friction. The 60000 N Car travels up the hill with
5N more than the component going down the ramp.
a = (m2*g)/(m1 - m2)
T = m2 * ((m2*g)/(m1 - m2))
d = ½((m2*g)/(m1 - m2))t2