Question

A block of mass m is moving due to a constant force act on it. If the mass were tripled but the force remained constant, the acceleration of the block would be

• A. Nine times as much
• B. Three times as much
• C. Unchanged
• D. One third as much
• E. One ninth as much

Answer 1

The correct option is D One third as much

Initial acceleration of the block $a=\frac{F}{m}$

Now the mass of the block is tripled keeping the force constant i.e $m^{\prime }=3m$

$\therefore$ New acceleration of the block $a^{\prime }=\frac{F}{3m}=\frac{a}{3}$

Thus the acceleration is reduced by 3 times.