Work

• The weightlifter does work by exerting a force and causing the barbell to undergo a displacement. This increases the gravitational potential energy of the barbell and decreases the store of chemical energy in the muscles of the weightlifter
• Work done by a force

  1. Force applied at an angle to the displacement, only the component of the force in the direction of the displacement contributes to the work done

  2. If force and displacement vectors are at an angle to each other, then Fcosθ is the component of the force that does the work

  3. W = Fs cosθ where W is the work done by the force (J), F is the magnitude of the constant force (N), s is the displacement (m), and θ is the angle between the force and displacement vectors
• To find the work done on an object, the net force needs to be used. For instance, if a person pushes a heavy couch across a carpeted floor, the work done that opposes the motion on the couch depends on the force applied by the person less the frictional force
• Work done by a force is given by the equation W = Fs where W is the work done by the force (J), F is the magnitude of the constant force (N), and s is the displacement (m)
• In physics, work is the transfer of energy from one object to another and/or the transformation of energy from one form to another
• While both force and displacement are vectors, work and energy are scalar quantities measured in joules (J)
• Work is done when a force acts on an object causing a displacement in the direction of the force
• When an unbalanced force acts on an object over a time interval, the object accelerates and its momentum changes. When the force causes a displacement in the direction of the force, the energy of the object changes, and work is done