A body of mass 2kg slides down with an acceleration of 3m/s² on a rough inclined plane having a slope of 30°. The external force required to take the same body up the plane with the same acceleration will be:(g=10m/s²)
20N
14N
4N
6N
Solution:
Equation of motion when the mass slides down Mgsinθ - f = Ma 10 - f = 6 f = 4N Equation of motion when the block is pushed up Let the external force be F F - Mgsinθ - f = Ma F - 10 - 4 = 6 F = 20N