Which of these examples best illustrates that work is not done according to physics?
A person holds a bag without moving it
In physics, work is done only when a force acts on an object and the object is displaced in the direction of the force: \(W = Fs\cos\theta\). If the displacement is zero, the work done is zero, however large the force.
A person holding a bag still applies an upward force to support it, and may even feel tired, but the bag does not move. So the displacement is zero and no work is done on the bag in the physics sense.
Lifting a book onto a shelf moves it upward in the direction of the applied force, and pulling a cart along a road or pushing a box across the floor moves the object along the force. In all three a force produces displacement, so work is done.
Hence, A person holds a bag without moving it.
Similar Questions
A stretched rubber band possesses which form of energy due to its changed shape?
Which situation involves an increase in potential energy?
A cart of mass 20 kg starts from rest and accelerates uniformly along a straight horizontal track. If it reaches a speed of 6 m/s in 3 seconds, what is the work done on the cart during this time interval?
What will be the power delivered by a lamp that uses 120 joules of energy in 2 minutes?
When a ball rolls down a hill and comes to rest, how is the total energy of the ball-earth system maintained?
Which of the following quantities is needed to calculate the work done by a constant force?
Which scenario demonstrates a higher power output, assuming the same work is done in each?
Simple machines are best described as devices that _______________.
A body of mass 2 kg kept at the top of a building of height 10 m possess a potential energy of 200 J. What will be the kinetic energy of this body when it hits the ground? (Neglect air resistance)
The kinetic energy of a body of mass 'X' kg is 200 J when it is moving with a velocity of 2 m/s. What will be the value of X?
Important Questions from Work Power Energy
Which of the following is NOT correct regarding friction?
If a pump can raise 200 liters of water through a height of 300 meters in one minute, how much work can it do in one hour?
Which of the following is an example of kinetic energy?
How much kinetic energy does a 160 g cricket ball have when it is thrown at a speed of 22 m/s?
The movement of birds is an example of _______.
