1 A particle of mass 8 kg is pulled at a constant speed a distance of 20 m up a rough plane inclined at an angle of \(30 ^ { \circ }\) to the horizontal by a force acting along a line of greatest slope.
- Find the change in gravitational potential energy of the particle.
- The total work done against gravity and friction is 1146 J . Find the frictional force acting on the particle.