P2 Flashcards
How is displacement different to distance?
Both are measures of how far something has travelled, but displacement includes direction. eg. 10m north
How is velocity different to speed?
It describes speed AND direction. eg. 30mph due north
What is a scalar quantity?
Quantities which only involve numbers, eg. speed, distance, mass, time
What is a vector quantity?
Quantities which also have a direction, eg. velocity, displacement, force, acceleration
How do you calculate distance travelled with speed and time?
Distance travelled (m) = Speed (m/s) * Time (s)
What is acceleration?
The rate of change of velocity.
How do you calculate acceleration with change in velocity and time?
Change in acceleration (m/s²) = Change in velocity (m/s) ÷ Time (s)
What does it mean if an object has negative acceleration?
It is either slowing down (decelerating), or speeding up in the negative/opposite direction.
What is uniform acceleration?
Constant acceleration
How do you calculate uniform acceleration with final velocity, initial velocity, acceleration and distance?
(final velocity (m/s))² - (initial velocity (m/s))² = 2 * acceleration (m/s²) * Distance (m)
v² - u² = 2 * a * d
What practical can you perform involving a trolley and a ramp to investigate the relation between distance, speed and acceleration?
Set up a ramp with 3 light gates on it, measure the distance between them.
When the trolley reaches the “runway”, it will travel at constant speed.
The time between 1 + 2 can be used for avg speed on the ramp, and the time between 2 + 3 gives the speed on the runway.
The acceleration of the trolley on the ramp can be found with the initial speed, 0, the final speed (speed on the runway) and the time between 1 and 2.
How big should your measuring instrument be?
If possible, longer than than the distance you’re measuring.
What could you use to measure time?
A stopwatch, although it involves human error.
Light gates connected to a computer.
What does the gradient on a distance-time graph show?
Speed of the object.
What does a flat section on a distance-time graph show?
When the object is stationary
What do curves on a distance-time graph show?
Acceleration
What does it mean if the gradient on a distance-time graph is increasing/decreasing?
The speed is increasing/decreasing.
How can you find the gradient of a specific point on a curve?
Draw a tangent to the curve at that point, and find the gradient of the tangent.
What does the gradient on a velocity-time graph show?
Acceleration
What does a flat section on a velocity-time graph show?
Constant/steady velocity
What do upwards/downwards sections on velocity-time graphs show?
Acceleration/decelleration
What does a curve on a velocity-time graph show?
Changing acceleration
What does the area beneath any section of a velocity-time graph show?
The distance travelled in that time interval
What are examples of contact and non-contact forces?
Contact - friction
Non-contact - electrostatic, magnetic, gravitational