How much work must be done on a 4.0kg frictionless trolley, to accelerate it from rest to a velocity of 5.0m/s?

It must firstly be noted that, in general, the work done on an object is equal to its gain in energy.The trolley has gained kinetic energy. This can be calculated using the formula: "KE = (1/2)mv^2" where 'm' is the mass of the object and 'v' is its new velocity, when accelerating from rest.The KE gained by the trolley = (1/2) m v^2                              = (1/2) x 4 x 5^2                              = 50 JSo the work done on the trolley is equal to 50J.