REVIEWER IN SCIENCE 8 Q1
REVIEWER IN SCIENCE 8 Q1
Force
- Forces are pushes or pulls that can cause objects to change their motion or shape. It has a magnitude and direction.
Acceleration=
Force= ma
Mass=
Balanced Forces
- When two or more forces acting on an object are equal in magnitude and opposite in direction
- the object remains at rest or mores with constant velocity.
- ex: A book resting on a table with no external forces acting on it.
Unbalanced Forces
- When the forces acting on the object are unequal
- there is a net force that causes the object to accelerate.
* Not all forces cause a change in motion. Which is why we have balanced force; Fnet=0
Acceleration
- the rate of change of velocity.
3 ways to say that a body is accelerating
1) Change in speed.
- speeding up
- slowing down
2) Change in direction
3) Change in both speed and direction
Newton's Law of Motion
-3 Laws of Motion
1) Law of Inertia
- a body at rest will remain at rest and a body. in motion will continue to move in a straight line w/ constant velocity unless acted upon by an external force.
- the basis of Inertia is the mass.
2) Law of Acceleration
- is directly proportional to the magnitude of the net force acting on it
- is inversely proportional to its mass
- if the net force increases. the acceleration will also increase
- the greater the mass, the lower the acceleration
3) Law of Interaction
- Newton's Third Law of Motion
- States that "for every action, there is an equal and opposite reaction"
- ex: Walking, swimming, Driving a car
Work and Energy
Work
- a way of transferring energy.
- When work is done by an object it loses energy and when work is done on an object it gains energy.
- The energy of an object enables it to do work.
Work is done
- If the object you push moves a distance in the direction towards which you are pushing it.
Work is not done
- If the force you exert does not make the object move. If the force you exerted does not make the object move in the same direction as the force you exerted.
F = force applied
d = displacement of the object
W = work done
unit of work = unit of force x unit of displacement
unit of work = Joules (J)
1) Kinetic Energy – energy of a moving object (energy of motion)
2) Potential Energy – energy gained or lost by an object/stored energy
3) Power – the rate of doing work or the rate of using energy
W = Fd PE = mgh
KE = 2 P =
Heat and Temperature
Heat
– is a form of energy
– heat transfers from an object of higher temperature to an object of lower temperature
– can be transferred through conduction, convection, or radiation
– “energy in transit”
Temperature
– a measure of the average kinetic energy of the particles
– does not depend on the mass of the object
Thermal Energy
– energy that is contained in an object due to the motion of its particles
Thermal Expansion
– effect of heat transfer; tendency of matter to change its shape, area, and volume in response to a change in temperature
Phase Change
– may occur when heat is added to or taken out from an object
Amount of heat transferred depends not only on the temperature of the material. It also depends on the mass or amount of material. Objects with greater mass have more thermal energy and can transfer more heat.
Heat Capacity
– amount of heat required to increase the temperature of one unit mass of a given material by one Celsius degree; specific heat capacity (c) calorie