While playing tug of war, Preeti felt that the rope was slipping through her hands. To prevent this, first she need to make her smooth hand non-smooth.

⇒ Because the friction decreases as the surface becomes smooth. Hence, the rope was slipping through her hands (smooth).

⇒ To make her hands non-smooth, she should apply sand on both the hands.

⇒ Due to the sand, her hands become non-smooth (rough)

⇒ Friction increases when the surface is rough.

⇒ As a result, friction increases between the rope and her hand and now the rope won’t slip through her hands.