Work Power and Energy

Work ,Power and Energy

by NIKHIL SIR

​Work

​Work is also...

Multiple Select

Work can be..

• Positive

• Negative

• Both positive and Negative

• Zero

Multiple Choice

How much work is done in holding a 15 N sack of potatoes while waiting in line at the grocery store for 3 minutes?

• 15 J
• 45 J
• 0 J
• 5 J

​Power

​time rate of doing work or delivering energy, expressible as the amount of work done W, or energy transferred, divided by the time interval t

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• SI unit Watt (W)

• Commercial unit Kw=1000 W

• 1HP =746 watt

Fill in the Blanks

Convert 1kw-hr of energy into Joules (J)

Multiple Select

Power is also

• $$P=F\times V$$  

  F=force

  V=velocity

• $$P=\frac{F.s}{t}$$  

  s=displacement

  F=force

• A scalar quantity

• A Vector quantity

" Energy can neither be created nor be destroyed, can only be changed from one form to another . " 

Energy

Energy possessed by an object due to its position or Configuration.

​

P.E.= mgh​ or P.E.= ½kx²

Potential Energy

Energy possessed by an object due to its motion.

​

K.E.= ½mv²​

Kinetic Energy

Mechanical Energy

M.E.= K.E.+P.E. Unit of Energy is J

Multiple Choice

Potential or kinetic?
Stretched bow and arrow?

• kinetic
• potential

Multiple Select

Select all: Work is equal to...

• KE + PE

• Change in energy

• mg

• Fd

Multiple Choice

How does conservation of energy explain why something that is falling should speed up?

• It gains kinetic energy because it gains potential energy.

• It loses kinetic energy because no work was done on it.

• It gains kinetic energy because it loses potential energy.

• It loses kinetic energy because the Earth gains potential energy.

Multiple Choice

At which point(s) on the roller coaster is the kinetic energy at its maximum?

• A
• B
• C
• D

Law of Conservation of Energy

Let's Proove it.​