The average acceleration of an object can be calculated using the equation:
acceleration = change in velocity/time taken
a = Δv/t
a = acceleration, in metres per second squared, m/s2
Δv = change in velocity, in metres per second, m/s
t = time, in seconds, s
An object that slows down is decelerating.
You should be able to estimate the magnitude of everyday accelerations.
The acceleration of an object can be calculated from the gradient of a velocity–time graph.
The distance travelled by an object (or displacement of an object) can be calculated from the area under a velocity–time graph.
Students should be able to:
draw velocity–time graphs from measurements and interpret lines and slopes to determine acceleration
interpret enclosed areas in velocity–time graphs to determine distance travelled (or displacement)
measure, when appropriate, the area under a velocity–time graph by counting squares.
The following equation applies to uniform acceleration:
final velocity2 − initial velocity2 = 2 × acceleration × distance
v2 − u2 = 2as
v = final velocity, in metres per second, m/s
u = initial velocity, in metres per second, m/s
a = acceleration, in metres per second squared, m/s2
s = distance, in metres, m
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Near the Earth's surface any object falling freely under gravity has an acceleration of about 9.8 m/s2.
An object falling through a fluid initially accelerates due to the force of gravity.
Eventually the resultant force will be zero and the object will move at its terminal velocity.
You should be able to:
draw and interpret velocity–time graphs for objects that reach
terminal velocity
interpret the changing motion in terms of the forces acting.
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