Types of Forces
A force that pushes up on an object resting on a surface
Normal Force
Friction that occurs when an object is NOT moving
Static Friction
Draw the following Force Diagram and Solve:
10 N right and 10 N left → net force?
0 N
An object at rest stays at rest unless acted on by…
An unbalanced force (1st Law)
A student pushes a cart across the floor. The cart has a mass of 3 kg and speeds up at 2 m/s². What force is applied to the cart?
6 N
Which TWO of these are non-contact forces?
Magnetic & Electrical
Why is rolling friction less than sliding friction?
Objects roll instead of scrape (less contact/resistance)
Draw the following Force Diagram and Solve:
20 N right and 5 N left → net force and direction?
15 N right
Which law explains F = ma?
Newton’s 2nd Law
A grocery cart is pushed with a force of 24 N. The cart has a mass of 6 kg. How quickly does the cart accelerate?
4 m/s²
A skydiver falling slows down because of which force?
Drag Force
A sled moving down a snowy hill experiences what type of friction?
Sliding Friction
If the net force is 0 N, what type of forces are acting?
Balanced forces
A swimmer pushes water backward and moves forward.
Newton’s 3rd Law
A dog pulls a sled with a force of 40 N, causing it to accelerate at 5 m/s². What is the mass of the sled?
8 kg
A book is sitting on a table. Name TWO forces acting on it.
Gravity + Normal Force
Which situation has the MOST friction:
Rough pavement and rubber shoes
Draw the following Force Diagram and Solve:
A box has 30 N up and 30 N down, and 20 N right and 5 N left. Net Force?
15 N right
A car stops suddenly and passengers move forward.
Newton’s 1st Law (inertia)
A box is pushed to the right with 50 N of force, but friction pushes to the left with 10 N. The box has a mass of 10 kg. What is the acceleration of the box?
Net force = 40 N → 40 ÷ 10 = 4 m/s²
A charged balloon sticks to a wall. What type of force is responsible AND is it contact or non-contact?
Electrical force, non-contact
A student wants to make their balloon car go farther. Name ONE change to reduce friction AND explain why.
Smoother wheels/surface → less friction → less energy lost
Draw the following Force Diagram and Solve:
A box has forces acting in both directions:
What is the net force AND is the motion changing?
30 N right, yes (unbalanced → motion changes)
Two students of different masses are pushed with the same force. Who accelerates more and why?
The smaller mass → less mass = more acceleration (2nd Law)
Two objects are pushed with the same force of 20 N.
Which object accelerates more, and why?
Object A → less mass → greater acceleration