Laws of Motion

Question : 6 of 40

Marks: +1, -0

A constant force acting on a body of mass 3.0 kg changes its speed from 2.0 m s

^{-1}

to 3.5 m s

^{-1}

in 25 s. The direction of the motion of the body remains unchanged. What is the magnitude and direction of the force?

Solution:

Here,

m=3.0\,\text{kg}, u=2.0\,\text{m}\,\text{s}^{-1};

v=3.5\,\text{m}\,\text{s}^{-1}, t=25\,\text{s}

Now,

v = u + at

3.5=2+a \times 25

\Rightarrow a=\frac{3.5-2}{25}

=0.06\,\text{ms}^{-2}

Therefore, force acting on the body,

F = ma = 3 \times 0.06 = 0.18\,\text{N}

in the direction of motion.

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