Question

A body displaces by 4m along a line making an angle of 60° with line of action of force of 10 N then work done by the force is:

○Zero

○10 j

○20 J

○40 J

​

Answer 1

Answer :

• Work done by the body which displaces by 4 m at an angle of 60° when a force of 10 N acts on it is 20 J.

Explanation :

Given :

• Displacement of the body, s = 4 m
• Angle on which the body is moving, θ = 60°
• Force applied on the body, F = 10 N

To find :

• Work done by the body, W = ?

Knowledge required :

• Formula for work done :

⠀⠀⠀⠀⠀⠀⠀⠀W = F s cosθ⠀

Where,

• F = Force applied on the body.
• s = Displacement of the body.
• θ = Angle on which the body is moving.

Solution :

By using the formula for work done and substituting the values in it, we get :

⠀⠀=> W = F s cosθ

⠀⠀=> W = 10 × 4 × cos30°

⠀⠀=> W = 10 × 4 × ½ ⠀⠀⠀⠀[∴ cos30° = ½]

⠀⠀=> W = 40 × ½

⠀⠀=> W = 20

⠀⠀⠀⠀⠀∴ W = 20 J

Therefore,

• Work done by the body, W = 20 J

Answer 2

$\huge{\boxed{\rm{Question}}}$

A body displaces by 4m along a line making an angle of 60° with line of action of force of 10 N then work done by the body is:

• Zero

• 10 J

• 20 J

• 40 J

$\huge{\boxed{\rm{Answer}}}$

$\large{\boxed{\boxed{\sf{Given \: that}}}}$

• A body displaces by 4m along a line making an angle of 60° with line of action of force of 10 N

Means,

• Displacement of the body = 4 m.

• Angle on which body is moving = 60°

• Action of force on the body = 10N

$\large{\boxed{\boxed{\sf{To \: find}}}}$

• Work done by the body is

$\large{\boxed{\boxed{\sf{Solution}}}}$

• Work done by the body is 20 J

$\large{\boxed{\boxed{\sf{We \: also \: write \: these \:}}}}$

• Unit of force as N.

• Angle on which body is moving as θ

• Displacement as s

• Joules as J

$\large{\boxed{\boxed{\sf{Using \: formula}}}}$

• Work done (formula)

W = F s cosθ

$\large{\boxed{\boxed{\sf{What \: does \: the \: question \: says}}}}$

$\large{\boxed{\boxed{\sf{Let's \: understand \: the \: concept \: 1st}}}}$

• This question says that there is a body displaces by 4 m along a line making an angle of 60° with line of action of force of 10 N then work done by the force is ? Some options are given below as hints.

❶ Zero

❷ 10 J

❸ 20 J

❹ 40 J

$\large{\boxed{\boxed{\sf{How \: to \: solve \: this \: question}}}}$

$\large{\boxed{\boxed{\sf{Let's \: see \: the \: procedure \: now}}}}$

• To solve this question we have to use only a rule to find work done by body and we already know that rule. The rule is W = F s cosθ. Now putting the values according to this formula we get our final result that is 20J . J mean Joules.

$\large{\boxed{\boxed{\sf{Full \: solution}}}}$

Now we have to out the values according to the formula to find work done. And the rule is W = F s cosθ.

Using formula,

• W = F s cosθ.

Where,

• W means work doned.

• θ means angle on which body is moving

• s means displacement.

Putting the values,

• W = F s cosθ.

• W = 10 × 4 × cos60°

• W = 40 × cos60°

The value of cos60° is ½

• W = 40 × ½

• W = 20

Hence, 20J is the answer.