Acceleration
Definition: Acceleration is the change in velocity in a period of time.
For this section, the definition of acceleration is key. Change in velocity over time is one of the key equations in Dynamics, and understanding acceleration makes velocity-time graphs far easier to read.
Acceleration Equation
Acceleration is the change in velocity over time.
You need to be able to plug in number values into the given equation.
a=(v-u)/t
Remember, the units for acceleration are meters/second/second, giving ms^-2.
On a velocity-time graph, any slopes indicate acceleration or deceleration. By calculating the GRADIENT of the line in a velocity-time graph, you can calculate the acceleration. This can be done by using m=(y2-y1)/(x2-x1) from Maths.
Experiments and Acceleration
A common question in exams is to describe an experiment for calculating the acceleration of an object. I’ll describe an experiment calculating the acceleration of a car rolling down a hill.
You require a timer, two light gates and a car with a card of known length on top.
Record the length of the card. Roll the car down the hill with light gates set up as shown. Record the time taken to cut the first light gate and the time taken to cut the second light gate.
Velocity at each gate can be calculated using the length of the card and the time to cut the light at each light gate. The differences in the values divided by the time between the gates gives you the acceleration of the car.
Key Points!
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Acceleration Definition
Acceleration is the change in velocity over time.
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Acceleration on a velocity-time graph
Acceleration between two points on a velocity-time graph can be found by calculating the gradient. (m = y2-y1/x2-x1)
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Describe an experiment for acceleration
Be able to describe an experiment to calculate acceleration of a car rolling down a ramp.