Physics Notes

PHYSICS NOTES

1. What is physics?

1. Physics is the study of the interactions of matter and energy.
2. Isaac Newton is considered the founder of modern physics.

1. Speed and velocity are similar because they both involve distance and time. They are different because velocity also includes direction.

Speed = Distance

Time

1. What is a force?

1. A force is a push or a pull. Force gives energy to an object, sometimes causing it to start moving, stop moving, or change direction. Friction, gravity, pushing and pulling are examples of forces.

1. There are two types of forces:
2. Balanced – forces that cancel each other out. The two opposing forces are equal.
3. standing
4. sitting
5. Unbalanced – a force that puts an object into motion. The two opposing forces are not equal.
6. hitting a tennis ball,
7. dialing the phone

1. Work

1. Work is the transfer of energy.
2. W = force x distance

1. Acceleration

1. Acceleration is the rate of change of velocity over time.
2. Ex. a car
3. Acceleration is measured in meters per second per second.
4. m/s2

1. Weight / Mass

1. Weight is a force. The measure of the force of gravity on an object.
2. Gravity = 9.8 m/s2
3. Weight (w) = mass (m) x acceleration due to gravity (g)

W = m * g

Unit for weight = kg * m/s2 = N (Newton)

1. Mass is the quantity of matter in an object.
2. Mass remains the same regardless of the influence of gravity.

1. Newton’s Laws of Motion

1. First Law of Motion – An object at rest will remain at rest, unless an unbalanced force acts upon it.

1. Second Law of Motion
2. When an unbalanced force acts on an object, the object will be accelerated. The acceleration will vary directly with the unbalanced force applied and will be in the same direction as the applied force. It will vary inversely with mass of the object.
3. In other words, the more force on an object, the more it accelerates, but the more massive it is, the more it resists acceleration.
4. Force = mass x acceleration (F = m*a)
5. This law explains how force and acceleration are related.

1. Third Law of Motion – If an object exerts a force on a second object, the second object will exert a force of equal strength in the opposite direction of the first object.

1. Friction

1. Friction is a force that acts in the direction opposite to the motion of the moving object.
2. Ex. Pushing a box up an incline
3. Friction will cause a moving object to stop or slow down.

1. Energy
2. Potential energy is stored energy
3. Elastic – objects that can be stretched or compressed.
4. Gravitational – energy depending on height
5. Kinetic energy is energy of motion

Kinetic energy = mass x velocity2

2

1. Specific Heat
2. The specific heat of a substance tells how much energy is needed to raise the substance’s temperature by a given amount.
3. The amount of energy required to raise the temperature of 1 kilogram of a substance by 1 Kelvin is the specific heat of a substance.
4. Materials with a high specific heat can absorb a great deal of thermal energy without a great change in temperature.
5. Kelvin is the Celsius temperature calculation + 273o.
6. –273 o C is absolute zero. So “0” on the Kelvin scale is absolute zero.
7. Joules per kilogram-Kelvin (J/kg*K) is the unit of measure for specific heat.
8. The energy gained or lost by an object is related to the mass, change in temperature, and specific heat of the material.

Change in energy =

Mass x specific heat x change in temperature