Question

A force of $6\, N$ acts on a body at rest and of mass $1\, kg$. During this time, the body attains a velocity of $30 \,m/s$. The time for which the force acts on the body is

• A. 7 seconds
• B. 5 seconds
• C. 10 seconds
• D. 8 seconds

Answer 1

Answer: (B)

Force $(F)=6 N$; Initial velocity $(u)=0$;
Mass $(m)=1 kg$ and final velocity $(v)=30 \,m / s$.
Therefore acceleration $(a)=\frac{F}{m}=\frac{6}{1}=6 \,m / s ^{2}$
and final velocity $(v)=30=u+a t=0+6 \times t$
or $t=5$ seconds.