Calculating Net Force

When calculating force, remember, force has direction.

Braden pushes on a box to the right with a force of 50 N, and Anthony pushes on the box to the left with a force of 60 N.

a. Draw a picture showing the forces.

b. What is the net force on the box?

c. What will happen to the box?

b. Fnet=10N Left

c. Box will move left.

Arielle is driving East and pushes down on the gas pedal in her car and causes the engine to give a force of 1000 N to the tires on the car. Air and ground resistance push back on the car to the West with a force of 850 N.

a. Draw a picture showing the forces.

b. What is the net force on the car?

c. The Car will speed up to the East.

b. 150N to the East

c. What will happen to the car?

A box is sliding down an icy hill at a constant speed.

a. Draw a picture showing the forces.

b. What is the net force on the box?

c. What will happen to the box?

b. 0 N

c. The motion of the box will not change.

For the box in question 3, Mark pushes against the box up hill with 40 N of force.

a. Draw a picture showing the forces.

b. What is the net force on the box?

c. What will happen to the box?

b. 40N up the hill

c. The motion of the box will continue down the hill, however the force being applied by Mark will slow down the box.

If Mark continues pushing this way for a longer time, what will happen to the box?

The box will start going up the hill.

For the box in question 3, Sua pushes against the box up hill with 40 N of force and Hilary pushes the box downhill with 40 N of force.

a. Draw a picture showing the forces.

b. What is the net force on the box?

c. What will happen to the box?

b. 0 N

c. The box will not change its motion.

For the box in question 3, Mike pushes against the box up hill with 40N of force and Arman pushes the box downhill with 50N of force.

a. Draw a picture showing the forces.

b. What is the net force on the box?

c. What will happen to the box?

b. 10N Down Hill

c. The box will speed up down the hill

For the box in question 3, Sam pushes against the box up hill with 40N of force and Natalia pushes the box downhill with 30N of force.

a. Draw a picture showing the forces.

b. What is the net force on the box?

c. What will happen to the box?

b. 10N Uphill

c. First slow down, then starts going uphill

For the box in question 8, how hard (and in what direction) would Sam need to push the box for the box to continue sliding down the hill at a constant speed.

a. Draw a picture showing the forces.

b. Reduce the force at which he is pushing by 10N.

For the situations in the following figures calculate the net force on the box. Remember to include direction!

a.

25N South

b.

c.

50N West

4N Right

d.

e.

20N Left

20N West

f.

36N Down

Make up a question like question 1 and have your neighbour answer it.