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HELUS Science 8 Ch2

A push or pull is called a ___. force
A ___ ___ is the type of force that is only exerted when two objects are touching. contact force
The type of force exerted on one object by another when the objects are not touching is called a ___ ___. noncontact force
Gravity, magnetic force, and electric force are types of ___ ___. noncontact forces
Because forces have magnitude and direction, they are ___. vectors
The unit for the magnitude of a force is the ___. newton
When one or more forces acts on an object, the forces ___. combine
The ___ ___ is the combination of all the forces acting on an object. net force
When the net force on an object is not zero, the forces are said to be ___ ___. unbalanced forces
The ___ of an object changes only if unbalanced forces are acting on it. velocity
___ ___ occur when the net force on an object is zero. Balanced forces
The motion of any object does not change if the forces acting on it are ___. balanced
The scientist ___ ___ explained how forces cause motion to change. Isaac Newton
Newton’s ___ ___ ___ ___ states that if the net force on an object is zero, an object at rest remains at rest, or, if the object is moving, it continues to move in a straight line with constant speed. first law of motion
If the net force on an object is zero, the ___ of the object doesn’t change. velocity
___ is the tendency of an object to resist a change in its motion. Inertia
Gravity is an attractive force between all objects that have ___. mass
The ___ ___ ___ ___ states that all objects are attracted to each other. law of universal gravitation
According to the law of universal gravitation, the force of attraction between two objects depends on their ___ and the ___ between them. masses, distance
The ___ of an object is the gravitational force exerted on it. weight
Weight is a force ___, having magnitude and direction. vector
On Earth, weight is proportional to ___. mass
The contact force that acts to resist sliding between two touching surfaces is called ___. friction
___ ___ is the force between two surfaces in contact that keeps them from sliding when a force is applied. Static friction
Static means “___ ___.” not moving
___ ___ opposes the motion of two surfaces in contact that are sliding past each other. Sliding friction
An ___ ___ is exerted by a material when it is stretched or compressed. elastic force
The force exerted on a stretched rubber band is an example of a ___ ___. tension force
The force exerted on a squeezed rubber ball is an example of a ___ ___. compression force
A table exerts a ___ ___ on a cup resting on its surface. normal force
The direction of a normal force is ___ to the surface of the object. perpendicular
By identifying the forces acting on an object, you can predict its ___. motion
Whenever an object’s speed or direction changes, an ___ ___ must be acting on the object. unbalanced force
When a resting object is acted on by an unbalanced force, the object will ___ in the direction of the unbalanced force. accelerate
An object’s speed will ___ when a net force acts in the same direction as the object’s motion. increase
An object’s speed will ___ when a net force acts in the opposite direction of theobject’s motion. decrease
Unbalanced forces can cause an object to speed up, slow down, or change ___. direction
A ball tied to a string and swung in a circle is an example of ___ motion. circular
During circular motion, the ___ ___ acts perpendicular to the velocity, toward the center of the circle. centripetal force
When an object changes speed or direction, its velocity changes, and the object is ___. accelerating
___ ___ ___ ___ states that the acceleration of an object equals the net force divided by the object’s mass. Newton’s second law of motion
In the equation representing Newton’s second law of motion, force is measured in ___and mass is measured in ___. newtons, kilograms
The units of acceleration are ___. meter/second squared
When the ___ ___ is zero, the acceleration is zero. net force
When the acceleration of an object is zero, the ___ is constant. velocity
When the net force is not zero, the velocity of the object ___. changes
___ ___ ___ ___ states that when one object exerts a force on a second object, the second object exerts an equal force in the opposite direction on the first object. Newton’s third law of motion
The forces two objects exert on each other are called ___ ___. force pairs
The forces in a force pair are equal in ___ and ___ in direction. size, opposite
One of the forces in a force pair is called the ___ ___ and the other force is called the ___ ___. action force, reaction force
Created by: jnosik