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 is the force acting?

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 is the force acting? (A) 30° (B) 45° (C) 60° (D) none of these

Tardigrade Admin · Accepted Answer

Let required angle is θ. Work done = change in KE ⇒ F s cos θ=40-0 ⇒ 20 × 4 cos θ=400 ⇒ θ=60°

Q. A block is moved from rest through a distance of $4 m$ along a straight line path. The mass of the block is $5 k g$ 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 is the force acting?

$3 0^{\circ}$

$4 5^{\circ}$

$6 0^{\circ}$

none of these

Let required angle is $θ$ .
Work done $=$ change in $K E$
$\Rightarrow F s cos θ = 40 - 0$
$\Rightarrow 20 \times 4 cos θ = 400$
$\Rightarrow θ = 6 0^{\circ}$

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

30∘

45∘

60∘