Basic Forces
What is a force?
A push or a pull
What scientist is credited with discovering universal gravitation?
Isaac Newton
What force acts between surfaces and opposes their motion?
Friction
What do we call forces equal in size and opposite in direction?
Balanced forces
What does a spring scale measure and in what units?
Force in Newtons
What device measures force?
As the mass of an object increases, what happens to the strength of its gravitational pull?
It increases
What do lubricants generally do to friction?
What do we call forces that are unequal in size?
Unbalanced forces?
A spring scale reads 4 Newtons for one object and 8 Newtons for another. How does the first object's weight compare with the second's?
It weighs half as much.
In what unit does a spring scale measure force?
Newtons
What is the name of the idea that every object attracts every other object?
Newtons Law of Universal Gravitation
What common lubricant is used in a car engine?
Zero Netwons
What is the variable an investigator changes called?
What is the difference between mass and weight?
Mass is the amount of matter in an object and weight is the measure of the force of gravity on an object
As the distance between two objects increases, what happens to the gravitational force between them?
It decreases
Why does rolling an item create less friction than sliding it?
Less surface area of the item is in contact with the other item it is moving on.
One kid pulls west with 175 Newtons while another kid pulls east with 200 Newtons. What is the net force and in which direction?
25 Newtons going east
What is the dependent variable?
What the investigator measures
What do we call empty space with no air to create air resistance?
On the moon, a heavier rock and a lighter rock are dropped together from the same height. In the absence of air, which hits the surface first?
They hit at the same time
As a parachute opens, the object attached to it slows down. What causes this and why?
Air resistance because the open parachute has a greater surface area and more air particles push up against it.
An airplane has the following forces as it takes off:
500 Newtons moving forward
100 Newtons of friction
200 Newtons of gravity
400 Newtons lifting up
In which direction will the airplane go and with how much force in both directions?
Forward and up with 400 going forward and 200 lifting up
In an experiment, what do we call the factors kept the same so the test is fair?
Controlled variables