Question | Answer |
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 |