Forces And Motion

Question 1

I’m distance time graphs, for an object moving at a constant speed, you can calculate its speed using this equation:

Answer 1

Speed (m/s) = distance travelled (m) / time taken (s)
- equation can also be used to calculate average speed

Question 2

What is acceleration

Answer 2

Increase in speed, an object’s change of velocity per second
(M/s^2)

Acceleration = change in velocity (m/s) / time taken for change (s)

Question 3

What is velocity

Answer 3

Speed in a given direction
(M/s)

Question 4

What is displacement

Answer 4

Distance in a certain direction (m)

Question 5

What is deceleration

Answer 5

Negative acceleration

Question 6

How to find acceleration from a velocity time graph

Answer 6

• the gradient of the line

Question 7

What does the area under a velocity time graph represent

Answer 7

Distance travelled

Question 8

What does the gradient represent in distance time and velocity time graphs

Answer 8

Distance time- gradient is speed
Velocity time- gradient is acceleration

Question 9

What is thinking distance

Answer 9

The distance travelled by the vehicle in the time it takes for the driver to react
Speed x reaction time

Question 10

What is braking distance

Answer 10

The distance travelled by the vehicle during the time the braking force acts

Question 11

What is stopping distance

Answer 11

Stopping distance = thinking distance + braking distance

Question 12

Factors affecting stopping distance

Answer 12

• Tiredness, alcahol and drugs increase reaction time
• the faster a vehicle is traveling, increases thinking and braking distance
• bad road conditions, on wet or icy roads drivers have to break with less force to avoid skidding increasing stopping distance
• poorly maintained vehicles may take longer to stop

Question 13

What is drag force
(When an object falls in a liquid)

Answer 13

• the fluid drags on the object because of friction between the fluid and the surface of the moving object
• the drag force on an object works the opposite direction of its weight, decreasing the objects acceleration.
• acceleration decreases as it falls, frictional force increases as it speeds up

Question 14

Velocity time graphs for falling objects with drag

Answer 14

• the graph has a curved line with a gradient that decreases with time
• the gradient decreases because as the velocity increases, the drag force increases from zero, therefore the acceleration decreases