laws of motion Flashcards
Force
A push or pull on an object
Contact force
A pressure pull on one object by another that is touching it
Contact forces can be weak like when you
press the keys on a keyboard
Contact forces can be strong such as when
large sections of rock moves causing an earthquake
Gravity
An attractive force that exists between all objects that have mass
Mass
The amount of matter in an object often measured in kilograms (kg)
Who developed a lot of universal gravitation
Sir Isaac Newton
What is the law of universal gravitation
That all objects are attracted to each other by gravitational force
What does the strength of a force depend on
The mass of each object in the distance between them
When the mass of one or both objects increase
the gravitational force between them also increases
The attraction between objects decreases as a
distance between the objects increases
Weight
The gravitational force exerted on an object
The gravitational force earth exerts on you is _______ than the force exerted by any other object
Greater
The object’s weight is ________ to its mass
proportional
Near Earth’s surface, the way of an object in Newton’s is about blank times its mass in kilograms
10
How much change in weight is there when the distance increases greatly
No significant change
An astronaut in space is still only about blank of what it is on earth
90%
Friction
A force of a system motion of two surfaces that are touching
Static friction
Prevent surfaces from sliding past each other
Up to a limit what does a static friction do
The strength of static friction changes to match the applied force
Sliding friction
Opposes the motion of surfaces sliding past each other
What happens when static friction reaches its limit between surfaces
The box will move
Fluid friction
Friction between a surface and a fluid
Air resistance
Fluid friction between the surface and air
What happens when you decrease the surface area towards the oncoming fluid
It decreases the air resistance against the object
What causes friction
The interactions between the tiny bumps on surfaces as they rub against each other. The bumps on each surface bed and exert a force on each other making it hard for the surface to slip over each other
What happens when a positive charge on one surface slides by negative charge on the other surface
An attraction occurs between the particles
What makes up all surfaces
Small particles (atoms and molecules)
What happens with less friction
Is easier for surfaces to slide past each other
What happens when you rub soapy hands together in the soapy water slightly separates the surfaces of your hands
It causes less contact between the microscopic dips and bumps and between the electrical charges of your hands
Net force
The combination of all the forces acting on an object
What happens when two or more forces act on an object
The forces combine
What happens when you combine forces in the same direction
The net force is the sum of the individual forces
What happens when you combine forces in opposite directions
the forces will cancel, resulting in a net force of zero and no movement.
Balanced forces
Forces acting on an object that combine and form a net force of zero
Unbalanced forces
Forces acting on an object that combined and form a net force that is not zero
What happens when equal forces act on an object in opposite directions
The net force on the object is zero
Newton’s first law of motion
If a net force of an object is zero the motion of the object has not changed. If something isn’t pushed it won’t move
According to news first law motion what do bounds forces cause in an object’s velocity
No change, which is true when an object is at rest or in motion
Terminal Velocity
The constant velocity reached when air resistance equals the force of gravity acting on a falling object
Newton’s first law of motion only applies to what
Balance forces acting on an object
What happens when unbalanced forces act on an object at rest
The object starts moving
What happens when an unbalanced force is act on already moving object
The object speed, direction of motion, or both change
Inertia
The tendency of an object to resist the change in its motion
On Earth friction can be what
Reduce but not totally removed
What has happened for an object to start moving
A first grader than a static friction must be applied to it
What else happens to keep the object in motion
force at least as strong as friction must be applied continuously
How do objects stop moving
Because friction or another force acts on them
Circular motion
Any motion in which an object is moving along a curved path
When will an object speed up
If acceleration points in the same direction as the velocity
When will an objects slow down
if the direction of the net force on an object is opposite to the direction an object moves
What is a way that unbalanced forces can change an object’s velocity
to change its direction
Another name for a change in velocity over time
acceleration
unbalanced forces can make an object accelerate by
changing its speed, its direction, or both
Inertia of the moving object and the centripetal force acting on the object produce what
the circular motion of the ball and the moon
what does newton’s second law of motion descrive
the relationship between an object’s change in velocity over time, or acceleration, and unbalanced forces acting on the object
centripetal force
In circular motion, a force that acts perpendicular to the direction emotion, towards the center of the curve
What does an object that experiences centripetal pedal force
Satellite
What path does a satellite tend to move along
A straight path because of inertia
What is essential pedal force that keeps a satellite in orbit by changing its direction
Gravity
noncontact force
A force that one object can apply to another object without touching
The gravitational force between objects __________ as the distance between the objects ___________
decrease, increase (line that goes down then to the right)
Static friction _______ from moving, sliding _________ the motion
prevents, slows
same strength equals
balanced
different strength equals
unbalanced
