Forces & Motion
What is the unit of force?
Newton
What does Newton’s First Law say?
An object stays at rest or moves at constant velocity unless acted on by a force
What is mass measured in?
Kilograms (kg)
What is a scalar quantity?
A value with only magnitude (size), no direction
Name one type of simple machine
Lever
What is the force that slows down moving objects?
Friction
What is Newton’s Second Law formula?
F = ma
What is the formula for weight?
Weight = mass × gravity (W = mg)
What is a vector quantity?
A value with both magnitude and direction
What is the effort in a lever?
The force applied to move the load
What is the normal force?
The force a surface exerts upward, balancing the weight of an object
If mass increases and force stays the same, what happens to acceleration?
Acceleration decreases
How is weight different from mass?
Weight depends on gravity; mass does not
Is mass a scalar magnitude or a vector magnitude?
Scalar, because it only has magnitude and no direction
What happens to the net force on an object when two equal forces act in opposite directions
The net force is zero, so the object does not accelerate
You push a cart and it moves faster and faster. Which law is this and why?
Newton’s Second Law—Force causes acceleration depending on mass
On the Moon, your weight is less. Why?
Because gravity is weaker on the Moon
How is scalar magnitude different from vector magnitude?
Scalar magnitude has only size; vector magnitude also includes direction
What part of the lever do you push or pull on?
The effort arm
A car is moving at constant velocity. What does this tell you about the forces acting on it?
The forces are balanced; net force is zero
Give an example of Newton’s Third Law
Christina decides!
If a person has 50 kg of mass, what is their weight on Earth? (g = 9.8 m/s²)
490 N
If two forces have the same magnitude but opposite directions, are they the same vector?
No, because vectors must have the same magnitude and direction
The forces and distances of a lever follow what relation:
E*Ed=R*Rd