# P3: Forces and Transport (OCR Gateway Physics)

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Speed

• speed= distance
•                time
• average speed= initial speed + final speed
•
• ^This is basically finding the mean of the speeds
• The speed limit is higher on motorways because it is usually straight (or has very gradual bends). There are also no pedestrians, therefore the limit is higher as there are less reasons for you to slow down or stop within a small amount of time.

Changing Speed

• speed: a value (how fast you travel)
• speed is a scalar- (size only)
• velocity: a value and direction
• is a vector
• has a size and direction
• a measure of distance travelled over time
• velocity= change in distance
•                    change in time

Acceleration

• acceleration (m/s²) = change in speed (m/s)
•                                         time (s)
• change in speed = final speed- starting speed!

• Newton's 1st Law of Motion:
• An object will be stationary or move at a constant speed unless acted on by an unbalanced force
• force (N) = mass (kg) x acceleration (m/s²)
• F=MA

Work and Power

• work is done when a force moves an object
• energy is needed to do work
• work is measured in joules (J)
• work done (J) = force (N) x distance moved (m)
• power is…