Work & Energy Flashcards
What are the conditions for work done?
- force should act on an object
- the object must be displaced
W = F x S
What is the unit of work done?
The unit of work done is Nm or Joules (J).
Define work done.
Work is said to be done when the force acting on an object causes a displacement in the direction of the force.
What is positive and negative work done?
- When force is applied in the direction of displacement, the work done is positive.
- When force is applied in the opposite direction of displacement, the work done is negative.
What is energy?
An object having the capability of doing work is said to possess energy.
What is the unit of energy?
The unit of energy is the joule (J). 1 J is the energy required to do 1 joule of work. A larger unit of energy called kilojoule (kJ) is used. 1 kJ = 1000 J.
What is kinetic energy?
Objects in motion possess energy. We call this energy kinetic energy. A moving object can do work. An object moving faster can do more work than an identical object moving relatively slowly.
K.E. = 1/2 * m * v^2
What is potential energy?
The energy transferred to an object is stored as potential energy, if it is not used to cause a change in the velocity of the object. Potential energy is the energy stored in an object due to its position or shape.
What is gravitational potential energy?
An object increases its energy when raised through a height because work is done on it against gravity while it is being raised. The energy present in such an object is gravitational potential energy.
G.P.E = mgh
What is the Law of Conservation of Energy?
Whenever energy gets transformed, the total energy remains unchanged. This is the law of conservation of energy. According to this law, energy can only be converted from one form to another; it can neither be created nor destroyed. The total energy before and after the transformation remains the same.
What is mechanical energy?
The sum of the kinetic energy and potential energy of an object is its total mechanical energy. We find that during the free fall of the object, the decrease in potential energy, at any point in its path, appears as an equal amount of increase in kinetic energy. (Here the effect of air resistance on the motion of the object has been ignored.)
What is power?
Power measures the speed of work done. Power is defined as the rate of doing work or the rate of transfer of energy.
power = work/time
What is the unit of power?
The unit of power is watt (W) or J/s. FOr expressing larger quantities of power kilowatt (kJ).
When is the concept of average power useful?
The power of an agent may vary with time. This means that the agent may be doing work at different rates at different intervals of time. Therefore the concept of average power is useful in such situations.
