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WAEC Physics 2014 Paper

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Question : 9

Total: 48

A car starts from rest and covers a distance of 40m in 10s. Calculate the magnitude of its acceleration

0.25ms^-2
0.80ms^-2
3.20ms^-2
4.00ms^-2

Solution:

Concept:

Use the equation of motion for uniform acceleration:

s = ut + \frac{1}{2}at^2

.

Explanation:

The car starts from rest, so initial velocity

u = 0

.

Given:

s = 40\ \text{m}

and

t = 10\ \text{s}

.

Substitute into

s = ut + \frac{1}{2}at^2

:

40 = 0 \times 10 + \frac{1}{2}a(10)^2

40 = 50a

a = \frac{40}{50} = 0.8\ \mathrm{m\,s^{-2}}

Answer:

The magnitude of acceleration is

0.80\ \mathrm{m\,s^{-2}}

.

Correct option: B.

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