# Science chapter 2 Motion Forces and energy

## 41 terms

### force

a push or pull exerted on an object (p44)

### net force

the combination of all forces acting on an object

### unbalanced forces

a nonzero net force, which changes an object's motion (p46)

### balanced forces

equal forces acting on an object in opposite directions (p46)

### mass

the amount of matter in an object (p49)

### newton

a unit of measure that equals the force required to accelerate 1 kilogram of mass at 1 meter per second per second (p53)

### friction

the force that acts to resist sliding between two touching surfaces

### sliding friction

slows down an object that slides.

### rolling friction

friction that occurs when an object rolls over a surface (p57)

### gravity

the force that pulls objects toward each other (p58)

### terminal velocity

the maximum velocity a falling object can achieve (p59)

### weight

the force of gravity on an object at the surface of a planet (p59)

### Give an example of sliding friction

brake pades on a car use sliding friction against the wheels to slow the car

### If the forces are __________ forces their effects do not cancel out and the motion of the objects change

unbalanced
(net force is not zero)

static friction

rolling friction

### newtons second law of motion

an object acted upon by force will accelerte in the direction of the force

### force =

mass X acceleration

gravity

### in order to know how a force will affect an objects motion, you must know

the direction of the force

### In a circular motion your direction is

constantly changing

### in a circular motion you are

constantly acceleration

### according to newtons second law if you are constantly accelerating

there must be a force acting on you at alltime

### the constant speed a falling object reaches when air resistance balance the force of gravity

terminal velocity

### Newtons 3rd law of motion

for every action there is an equal but opposite reaction

### there is no delay in time between

the action and reaction (newtons 3rd law)

### when you push on a wall

the wall pushes back on you with a force equal in strength to the force you exert

### find the force on a 5 kg object that has an acceleration of 8 m/s2

f= m x acceleration

motion

sliding friction

kg x m/s2

force

static friction

### an aobject is accelerated by a net force in which direction

in the direction of the force

### if you exert 8N on a 2 kg object what will its acceleration be

force = M x acceleration so
acceleration = force/m. answer is 4 m/s2

### you are riding a bike in which of the following situations are the forces acting on the nike balanced

you pedal at a constant speed.

mass

5 N

### Newtons first law of motion

States that objects at rest will remain at rest or move with a constant velocity unless a force is applied.

### Newtons first law of motion

An object at rest will remain at rest or an object in motion at constant speed in a straight line unless acted upon by an unbalanced force