Work and energy Flashcards
What is the formula for calculating work done?
Work done = Force x Distance x cos(θ)
True or False: Work is a scalar quantity.
True
What unit is work measured in?
Joules (J)
If a force of 10 N moves an object 5 m in the direction of the force, how much work is done?
50 Joules
Fill in the blank: The work-energy principle states that the work done on an object is equal to the change in its ______.
kinetic energy
What is the formula for kinetic energy?
Kinetic Energy = 0.5 x mass x velocity²
What is the unit for energy?
Joules (J)
True or False: Potential energy is energy stored due to an object’s position.
True
What is the formula for gravitational potential energy?
Potential Energy = mass x gravitational field strength x height
What does ‘g’ represent in the gravitational potential energy formula?
Gravitational field strength, approximately 9.81 N/kg on Earth
What is the principle of conservation of energy?
Energy cannot be created or destroyed, only transformed from one form to another.
Fill in the blank: The unit of power is the ______.
Watt (W)
How is power related to work and time?
Power = Work done / Time taken
If 100 Joules of work is done in 5 seconds, what is the power output?
20 Watts
True or False: Machines can create energy.
False
What is mechanical energy?
The sum of kinetic and potential energy in a system.
What is the formula for elastic potential energy?
Elastic Potential Energy = 0.5 x spring constant x extension²
In the context of work and energy, what does ‘θ’ represent?
The angle between the force and the direction of motion.
True or False: Work can be negative.
True
What is the effect of friction on work done?
Friction opposes motion, reducing the work done on an object.
Fill in the blank: The total mechanical energy of a system remains constant in the absence of ______.
non-conservative forces (like friction)
What is an example of a non-conservative force?
Friction
What happens to kinetic energy when an object comes to a stop?
It is transformed into other forms of energy, such as thermal energy.
What is the relationship between work and energy in terms of units?
Both work and energy are measured in Joules.
True or False: Power is the rate at which work is done.
True
What is the significance of a positive work value?
It indicates that energy is being added to the system.
