Transformation of energy is the conversion or changing of energy from one form to another. Example
a.the ball is dropped from edge of cliff. Here the Potential energy of the ball is converted into Kinetic energy
b. In electric motor, electrical energy is converted into mechanical energy
a. Force must acts
b. Displacement should happen
An object having capability to do work is said to possess energy.
Energy has the same unit as that of work
Work done on an object is defined as the magnitude of the force multiplied by the distance moved by the object in the
direction of the applied force.
$W=F \times d$
The SI unit of work is joule:
$1 \; joule = 1 \; newton \times 1 \; metre$
Let $v_1$ and $v_2$ be the velocities of 10 kg and 50 kg mass
As the momentum is same
$10v_1 = 50v_2$
or
$\frac {v_1}{v_2} = 5$
Now
$K_1= \frac {1}{2} \times 10 \times v_1^2$
$K_2= \frac {1}{2} \times 50 \times v_2^2$
$K_1 : K_2 = \frac {1}{5} \times \frac {v_1^2}{v_2^2} = 5$
Zero as Force acting is perpendicular to displacement
a. The muscular energy of the cyclist is converted into rotational energy of the pedals of the bicycle which is transferred to its wheels. The kinetic energy of the rotation of the wheels is converted into the kinetic energy of the bicycle.
b. Chemical energy to heat, light, and sound energy.
The energy possessed by a body due to its change in position or shape is called the potential energy.
The gravitational potential energy of an object of mass, m raised through a height, h from the earth�s surface is given by
$PE= mgh$
SI unit of Potential energy is Joule
work done by the force of gravity on a satellite moving round the earth is zero as force of gravity acts at right angle(90°) to the direction of the motion of the satellite.So there is no displacement in the direction of force
An object in motion possesses what is known as the kinetic energy of the object. An object of mass, m moving with velocity v has a kinetic energy given by
$K= \frac {1}{2} mv^2$
SI unit is Joule
1 watt is the power of an agent, which does work at the rate of 1 joule per second
1 W= 1 Joule/s
Power = Energy /time = 1000/10 =100 W
Potential energy and Kinetic energy.
a. A body in free fall possess both the Kinetic energy and potential energy
Workdone =change in Kinetic energy = $0 - \frac {1}{2}mv^2 = - \frac {1}{2} \times 1000 \times 400= -200000 J=-200 KJ$
Gravitational potential energy does not depend on the path along which the body is moved, while going from one point to another
Consider the below figure
A block is moved from position A to B by two path
a. AB : Work done againts gravity = mgH
b. ACDB :
Workdone on moving the block A to C = zero ( As gravity is perpendicular to motion)
Workdone on moving from A to D = mgH
Workdone on moving the block D to B = zero ( As gravity is perpendicular to motion)
Therefore, total workdone=mgH
Hence Gravitational potential energy does not depend on the path along which the body is moved, while going from one point to another
Since the initial and final point lies on the same horizontal line, work done by the force of gravity on the object will be zero
a. solar energy to electric energy
b. electrical energy to mechanical energy
c. Electric energy to sound energy
d. Chemical energy to heat energy and then heat energy to mechanical energy and which is then finally converted into electrical energy
e. Potential energy to kinetic energy and then electrical energy
Yes. Body can still have energy in the form Potential energy
No. Since mechanical energy is zero, there is no potential energy and no kinetic energy. Kinetic energy being zero, velocity is zero. Hence, there will be no momentum.
The energy possessed by a body due to its change in position or shape is called the potential energy. SI unit is Joule
The gravitational potential energy of an object of mass, m raised through a height h from the earth�s surface is given by m g h. So Potential energy depends on mass and height
a. When height is changed, potential energy is changed
b. if mass is changed,potential energy is changed
$K= \frac {1}{2} mv^2$
$K= \frac {1}{2} \times 750 \times (15)^2= 84375 J$
When passenger of mass 50kg sit in the car, Total mass becomes =750 +50=800 kg
$K= \frac {1}{2} \times 800 \times (15)^2= 90,000 J$
$p=mv$ or $v= \frac {p}{m}$ -(1)
$K=\frac {1}{2} mv^2$ -(2)
Substituting the value v from (1) in (2)
$K= \frac {1}{2} m (\frac {p}{m})^2$
$K=\frac {p^2}{2m}$
$K= \frac {1}{2} mv^2$
$K= \frac {1}{2} \times 500 \times (5)^2= 6250 J$
When two passenger of mass 50kg sit in the car, Total mass becomes =500 +2*50=600 kg
$K= \frac {1}{2} \times 600 \times (5)^2= 7500 J$
Height climbed =30 * 20 =600 cm =6 m
Weight =50*10=500 N
Power = Workdone/time = 500 *6/30 = 100 W
