Question

How much work is done against gravity in lifting a 3kg object through a distance of 40cm?

Answer 1

Answer : 11.8JTo lift a 3kg object at constant speed,an upward force equal in magnitude to its weight,mg=(3)(9.8N)mg=(3)(9.8N),must be exerted on the object.The work done by this force is what we refer to as the work done against gravity :Work against gravity = mghmgh=[(3)(9.8)N](0.40m)=[(3)(9.8)N](0.40m)=11.8J