Question

When two forces, applied on an object are equal and opposite, then these forces ________ a)may move the object , b)may stop a moving object , c)may move the object and cause a change in shape, d)does not move an object but may cause a change in shape

Answer 1

may stop a moving object

Answer 2

When two forces, applied on an object are equal and opposite, then these forces, do not move an object but may cause a change in shape (Option - d)

• Equal and opposite forces cancel each other as they are in opposite directions and hence net external force on the body is zero ∴ the object will not move.
• The Resultant force - Fr is calculated by the given formula: $\sqrt{F^{2} _{1} + F^{2} _{2} + 2F_{1}F_{2} cos\alpha }$
• Here F₁ = F₂ = F and both in opposite directions then, in straight line α = 180.
• Fr =$\sqrt{F^{2} + F^{2} + 2F^{2} cos180 }$, cos 180 = -1
• Fr = $\sqrt{F^{2} + F^{2} - 2F^{2}$
• Fr = $\sqrt{2F^{2} - 2F^{2}$
• Fr = 0
• But, this force can cause a change in the internal shape of the body without changing its position.