Question

A force of $5$N, making an angle $\theta$ with the horizontal, acting on an object displaces it by $0.4$m along the horizontal direction. If the object gains kinetic energy of $1$J, the horizontal component of the force is?

• A. $1.5$ N
• B. $2.5$ N
• C. $3.5$ N
• D. $4.5$ N

Answer 1

The correct option is B $2.5$ N

$F=5N$
$S=0.4m$
Gain in K.E = Work done $W=1J=1N.m$
$=FS\cos \theta$
$=\left(F\cos \theta \right)S$
$=0.4\left(F\cos \theta \right)$

Horizontal component of force $=\cos \theta =\frac{1J}{\left(0.4m\right)}=2.5N$