Which of the following statement(s) is /are true regarding the work done by a constant force acting on a body? (i) The work done by the force can never be zero. (ii) If the direction of the force and displacement of the body is same, the work done will be positive. (iii) The S.I. unit of work done is joule.
Both (ii) and (iii)
The work done by a constant force is given by \(W = F \cdot d \cdot \cos\theta\), where \(\theta\) is the angle between the force vector and the displacement vector.
Statement (ii) — work depends on the angle between the force and displacement — is TRUE. Statement (iii) — if \(\theta = 90°\) (force perpendicular to displacement), \(\cos 90° = 0\) so no work is done — is also TRUE. Statement (i) — that work is always equal to F × d regardless of direction — is FALSE because the cosine factor must be included.
The correct answer is : Both (ii) and (iii).
Similar Questions
The work done in carrying a block of mass 30 kg to a height of ‘X’ m is 6000 J. What will be the value of X (in m)?
(Take the value of \(g = 10\ \text{m/s}^2\))
A stone of mass 500g is raised from ground to a height of 20 m. What is the gain in its potential energy?
(Take g=10 m/s2)
Important Questions from Work Power and Energy
A boy raises a box with a weight of 120 N from a height of 2 m. The work done by him is ________.
While releasing the arrow from a stretched bow, the Potential Energy of the bow is converted into?
Which is the main source of almost all energy on Earth?
Area under constant velocity – time curve equals ________ of the object over a given time interval.
If a body of mass is m, linear momentum is p and kinetic energy is K, then which of the following expressions is true?
