In all three equations of motion, the acceleration is assumed to be ________.
Constant
The three equations of motion relate initial velocity u, final velocity v, acceleration a, time t and displacement s for a body moving in a straight line: \(v = u + at\), \(s = ut + \frac{1}{2}at^2\) and \(v^2 = u^2 + 2as\).
They are derived from the velocity–time graph of a body whose velocity changes by equal amounts in equal intervals of time, which is a straight line. Its slope gives the acceleration, and a straight line has the same slope throughout.
So the derivation holds only when the acceleration has a single fixed value, that is, for uniformly accelerated motion. Free fall near the Earth, with a = g, is a common example where they apply.
If the acceleration were increasing, decreasing or random, the velocity–time graph would be a curve, and these simple equations would not apply; calculus would be needed instead. Therefore the acceleration is assumed to be constant.
Hence, Constant.
Similar Questions
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Important Questions from Motion
An object is covering distance in direct proportion to the square of time elapsed. What conclusion can be drawn about the motion of the object?
If the distance time graph of the motion of an object is a straight line but not parallel to the time axis, then it may be concluded that the object is moving with a:
Vehicles have treaded tires so that it_______.
What is the formula for momentum?
Momentum of a given body is doubled. Its kinetic energy becomes (mass not changed)
