Unit 5 Study Guide Physical Science

Isha Chaudhary

Physical Science

11/29/22

Mr. Lola

Unit 5 Study Guide

Motion – The change in position of an object from one place to another.

Reference Point – An object used to determine motion; it is usually a stationary object. (i.e., house, trees, earth)

Speed – The distance traveled divided by the time interval during which the motion occurred. (Formula Speed=distance/time) (Units meters/second)

Velocity – The distance traveled divided by the time interval during which the motion occurred WITH direction. (Formula Velocity = distance/time with direction. (Units = meters/seconds w direction)

Acceleration – The rate at which velocity changes over time. (Formula Acceleration = final velocity-starting velocity /time) (Units = meters/seconds/second/ or meters/ second squared)

3 Ways for an Object to Accelerate

1. Speed Up
2. Slow Down
3. Change Direction

Force – A push or a pull.

Newton – The unit used to measure force. (N)

Net Force – The combination of all forces acting on an object

Forces in different directions

5N=========>

Forces in same direction

5N======> +5N===========> = 10N==============>

Balance Forces – When the forces on an object create a ZERO net force. Do not cause a change in motion.

Unbalanced Forces – When the forces on an object DO NOT create a ZERO net force. Will cause an object to speed up, slow down or change direction.

Friction – A force that opposes motion between two surfaces that are in contact. Rough surfaces cause more friction than smooth surfaces.

3 Types of Friction

1. Sliding
2. Rolling (wheels)
3. Fluid (moving through gas or liquid)

Friction can be helpful (tire treads) or harmful (engine wear).

Ways to Reduce Friction

1. Put it on wheels
2. Use a lubricant
3. Smooth the surface
4. Remove mass

Gravity – A force of attraction between objects because of their masses.

Law of Universal Gravitation – States that all matter in the universe is attracted to all other matter.

Factors that Determine Gravitational Attraction

1. Mass (greater mass means greater gravity)
2. Distance (closer the objects are the greater the attraction)

Weight and Mass – Mass is universal, it stays the same, but weight can change due to differences in gravity, (i.e., the moon and earth have different gravitational forces).

Gravitational Constant – The rate at which things accelerate due to gravity. On Earth the Gravitational Constant is 9.8 m/s/s.

Formula for Acceleration Due to Gravity – Change in velocity = 9.8 m/s/s x time (secs). Example 9.8 m/s/s x 5 secs = 49 m/s

Air Resistance – A force that opposed the downward motion of a falling object.

Terminal Velocity: The point where gravity's downward force is balanced by the upward force of air resistance. The object continues to fall, but its velocity no longer increases.

Newton’s 1st Law – The law of Inertia. An object at rest stays at rest, an object in motion stays in motion at a constant speed in a straight line unless acted upon by an unbalance force.

Newton’s 2nd Law – Force = mass x acceleration Newtons = Kg. x m/s/s

Newtons 3rd Law – Action/Reaction. For every action there is an equal and opposite reaction. Force act in pairs.