Weight / Mass
This is the standard unit for mass.
What is the kilogram (kg)?
In the absence of air resistance, all objects fall with this acceleration on Earth.
What is 9.8 m/s² (or g)?
This is the force that opposes motion between two surfaces in contact.
What is friction?
This law states that an object at rest stays at rest unless acted upon by an unbalanced force.
What is Newton's First Law (or the Law of Inertia)?
This is the upward force exerted by a surface on an object resting on it.
What is the normal force?
Weight is calculated by multiplying mass by this value on Earth, approximately 9.8 m/s².
What is gravitational acceleration (or g)?
This is the only force acting on an object in true free fall.
What is gravity (or weight)?
This type of friction acts on an object that is not moving but is being pushed.
What is static friction?
According to Newton's Second Law, Force equals mass times this.
What is acceleration?
For an object sitting at rest on a table, these two forces are balanced.
What are weight (or gravity) and normal force?
A 5 kg object on Earth weighs 49 N. On the Moon where g = 1.6 m/s², this would be its weight.
What is 8 N?
A ball is dropped from rest. After 3 seconds, this is its velocity (ignore air resistance).
What is 29.4 m/s (or 3g)?
The force that resists motion in a fluid.
What is fluid friction?
Newton's Third Law: For every action, there is an equal and opposite one of these.
What is reaction?
This is the force exerted by a rope.
What is the tension force?
This remains constant whether you're on Earth, the Moon, or in space, unlike weight.
What is mass?
An object is thrown upward at 20 m/s. This is the time it takes to reach its maximum height.
What is 2.04 seconds (or approximately 2 seconds)?
The force that resists motion when an object is sliding.
What is sliding friction?
A 1500 kg car accelerates from rest to 20 m/s in 5 seconds. This is the net force on the car.
What is 6000 N?
The point of drawing freebody diagrams is to keep track of forces such that you can apply this law.
What is newton's 2nd law?
An astronaut has a mass of 80 kg. On a planet where they weigh 1200 N, this is the planet's gravitational acceleration.
What is 15 m/s²?
A stone is dropped from a cliff and hits the ground after 4 seconds. This is the approximate height of the cliff.
What is 78.4 meters (using h = ½gt²)?
Unlike kinetic friction, this type of friction can vary in magnitude up to a maximum value.
What is static friction?
A 50 kg person stands on a scale in an elevator. When the elevator accelerates downward at 2 m/s², this is the reading on the scale.
What is 390 N?
A 10 kg box is pushed across a floor with 80 N of force. With 30 N of friction, this is the box's acceleration.
What is 5 m/s²?