Question

A block is moved from rest through a distance of $4$m along a straight line path. The mass of the block is $5$ kg and the force acting on it is $20$N. If the kinetic energy acquired by the block be $40$J, at what angle to the path the force is acting?

• A. ${30}^o$
• B. ${60}^o$
• C. ${45}^o$
• D. None

Answer 1

Answer: (B)

${60}^o$

$FSCos\theta =K.E$
$Cos\theta =K.E/\left(FS\right)$
$Cos\theta =40/(20\times 4)$
$Cos\theta =1/2$
$Cos\theta =Cos{60}^{\circ }$
$\theta =60°$