# Science exam-force and motion

## 31 terms

### force

a push or pull that acts on an object

### newton

a unit named after Sir Isaac Newton that measures force. N=kgm/s^2

### friction

a force that opposes tha motion of ovjects that touch as they move past each other.

### static friction

the friction force that acts on non-moving objects and always acts in the opposite direction of the applied force

### sliding friction

a friction force that opposes the direction of an object as it slides over a surface.

### rolling friction

a friction force that acts on rolling objects

### fluid friction

a friction force that opposes the motion of an object through a fluid

### air resistance

fluid friction acting on an object through air

### gravity

a force that acts between any two masses. It causes objects to accelerate downward.

### projectile motion

the motionof a falling object after it is given an initial forward velocity

### inertia

the tendency of an object to resist a change in its motion

### mass

a measure of the amount of matter in an object

### weight

the force of gravity acting on an object

### momentum

the product of an objects mass and velocity

### conservation of momentum

means that momentum does not increase or decrease

### constant speed

when the speed of an object doesnt change

### average speed

the total distance traveled divided by the time it takes to travel that distance

### instantaneous speed

the rate at which an object is moving at a given moment in time

### average acceleration

the average rate at which velocity increases

### balanced force

occurs when the net force of an object is zero and there is is no change in the object's motion

### unbalanced force

occurs when the forces on an object cause the object to accelerate.

### net force

the overall force acting on an object after all the forces are combined

### distance

the length of the path between two points.

### displacement

the direction from the starting point and the length of a straight line from the starting point to the ending point.

### law of gravitation

states that every object in the universe attracts to every other object.

### parallax

the apparent displacement of an object as seen from two different points that are not on a line with the object

### newton's first law of motion

states that the state of motion of an object does not change as long as the net force action on the object is zero.

### newton's second law of motion

states that the acceleration of an object is equal to the net force acting on it divided by the object's mass

### newton's third law of motion

states that whenever on object exerts a force on a second object, the second object exerts an equal and opposite force on the first object.

### scalars

quantities that express magnitude only, such as speed and distance

### vectors

quantities that express magnitude and direction