Find the force required to produce an acceleration of $8.8 \mathrm{m}/{\mathrm{s}}^2$ on a body of weight $7.8 \mathrm{N}$. Take $\mathrm{g} =9.8 \mathrm{m}/{\mathrm{s}}^2$.

The rate of change of a body's linear momentum is directly proportional to the external force applied to the body, and this change always occurs in the direction of the applied force.

As a result,

$\mathrm{Force} = \mathrm{mass}\times \mathrm{acceleration}$

According to the question given that,

Acceleration $\mathrm{a} = 8.8 \mathrm{m}/{\mathrm{s}}^2$

Weight of the body = 7.8 N

Since, $\mathrm{Weight} \mathrm{of} \mathrm{the} \mathrm{body} = \mathrm{mg}$

 $\mathrm{Mass} = \frac{\mathrm{weight}}{\mathrm{g}}=\frac{7.8 \mathrm{N}}{9.8 \mathrm{m}/{\mathrm{s}}^2}= 0.79 \mathrm{Kg}$ 

We know that,

According to the second law of motion, $\mathrm{F} = \mathrm{m}\times \mathrm{a}$

$$\begin{gathered} \mathrm{F} = 0.79 \mathrm{Kg}\times 8.8 \mathrm{m}/{\mathrm{s}}^2 \\ = 6.952 \mathrm{N} \end{gathered}$$

Hence, the correct answer is 6.9 N.