Which of the following statements is/are NOT true regarding the work done by a constant force acting on a body?
(i) The work done by the force can never be negative.
(ii) If the direction of the force and displacement of the body is same, the work done will be positive.
(iii) The S.l. unit of work done is Pascal.

Correct option is D

The correct answer is (d) Both (i) and (iii)

Explanation:

• Work (W) in basic physics is quantitatively defined as the product of applied force (F) and displacement (s) in the direction of the force. It is expressed as:
W = F × s × cosθ

• Statement (i) is NOT true because work can be negative. This happens when the applied force and displacement act in opposite directions (θ = 180°), such as the resisting work done by friction.

• Statement (ii) is true because when the applied force and displacement act in the same direction, cos(0°) = 1, resulting in positive work.

• Statement (iii) is NOT true because the standard S.I. unit of work is the Joule (J), while Pascal (Pa) is the unit used for measuring pressure.

• Therefore, both statements (i) and (iii) are incorrect.

Information Booster:
• Work done becomes zero when the applied force is perpendicular to displacement (for example, a person carrying a load horizontally on their head while walking).

• One Joule is defined as the work done when a force of 1 Newton moves an object by 1 meter in the direction of the force.

Additional Knowledge (Options Analysis):

Only (ii) (Option a)
• This option incorrectly identifies the true statement as false.

Only (i) (Option b)
• Although statement (i) is false, this option ignores statement (iii), which is also false.

Both (ii) and (iii) (Option c)
• This option incorrectly includes statement (ii), which is scientifically correct.