Forces

Question 1

what is a force?

Answer 1

• a push or pull
• a vector quantity
• can cause a change in the state of motion
• accelerate/decelerate/deform
• action + reaction

Question 2

force vectors need? (4)

Answer 2

1. magnitude
2. direction
3. line of action
4. point of application

Question 3

internal vs. external forces

Answer 3

internal: act within the object or system
- land from a jump; force from lower leg on upper leg through knee
- pulling forces are tensile forces
- pushing forces are compressive forces
- things rupture/break when these forces are too much

External: forces from the surroundings that act on an object

• include contact and non-contact forces
• non-contact includes gravity, magnetic, electrical

Question 4

contact forces

Answer 4

• can be solid or fluid
• air resistance and water resistance
• resolved into components parallel/perpendicular to the contact surface

Question 5

friction

Answer 5

proportional to the normal force, acts perpendicular to it

Ffr=uN