The total mass of the things on the road is 60 + 13, which is 73kg.
mass • acceleration = F
73 x 0.9m/s^2 = 65.7N
F = 65.7 N
Work is Force x Distance in the Direction of the force.
A line that is falling towards the x axis represents an object that is negatively accelerating, or slowing down. When the line hits the x axis, the object has stopped moving. If the graph continues below the x axis, the object has changed direction and is moving backwards at increasing velocity.
Answer:
By the law of conservation of mechanical energy, in the absence of any drag, when the rock falls towards the ground, the potential energy gets converted to kinetic energy. Once the rock hits the ground, it does not move. This is because, the energy is dissipated as sound or heat (to the environment). The total energy remains conserved. Only the form of energy changes.
