Physics Year 10 Term 1: Speed, Distance, Time, and Motion Graphs

Speed, Distance and time

How fast an object moves in a certain time. How far an object travel. How long the object took to travel.

Instantaneous Speed

Measures how quickly an object is moving at any one moment in time.

Average Speed

Average of instantaneous speed over a particular time period

Calculate distance, speed and time

THE TRIANGLE

Slope of distance/time graph

The speed of the object.

Flat regions in distance/time graph

Means the object has stopped.

Positive gradients in distance/time graph

Means the object is moving forwards.

Negative gradients in distance/time graph

Means the object is moving backwards.

Crossing 0 in distance/time graph

Indicates the object has gone back to its original starting point.

Curving vertical in distance/time graph

Indicates the object is accelerating.

Curving horizontal in distance/time graph

Indicates the object is decelerating.

Slope of speed/time graph

The acceleration of the object.

Flat region in speed/time graph

Means the object is going at a constant speed.

Positive gradients in speed/time graph

Means the object is accelerating.

Negative gradients in speed/time graph

Means the object is decelerating.

Crossing 0 in speed/time graph

Indicates the object has stopped.

Area under the curve in speed/time graph

Represents the distance that the object has travelled.

Displacement

Distance straight from starting to ending point

Scalar quantity

Doesn't have direction and has magnitude. Example is distance

Vector Quantity

Has direction and magnitude. An example is displacement

A drone went 800 m due east and then 200 m due west.

Determine the distance travelled and its displacement.

Distance: 1000 m, displacement: 600 m east

Velocity

Speed of object in a certain direction

Average velocity formula

Displacement/time

The vehicle travelled 5200 m in 480 s. It ended up 1440 m north east of its starting point. Calculate the vehicle's average speed and average velocity in that 480 s.

Speed: 10.8 m/s, velocity: 3 m/s north east

Positive and negative velocity

anything moving in the positive direction has a positive velocity, and anything moving in the negative direction has a negative velocity

Acceleration

Acceleration is change of velocity and is when an object speeds up, slows down or changes direction. It is measured in m/s/s, m/s2 , ms-2

Acceleration formula

velocity/time

Gannets are sea birds that dive at high speed into the water to catch fish. A particular gannet is going 28 m/s (100 km/h) when it enters the water. Half a second later, 10 m down, it has slowed to 14 m/s.

Calculate its average acceleration over this period.

-28m/s/s

A vehicle starting at rest is accelerated at 2.5 m/s/s. Determine the time taken to reach a velocity of 5 m/s.

2 seconds