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Work, Energy and Power

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Physics Part I

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Physics

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CBSE Gujarat Board Haryana Board

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Class 10 Class 12
A body is initially at rest. It undergoes one-dimensional motion with constant acceleration. The power delivered to it at time t is proportional to,    
  • (i) t1/2 

  • (ii) t  

  • (iii) t 3/2

  • (iv) t2


B.

(ii) t  

Tips: -

From,

v = u + at

v = 0 + at = at 

As power, P = F × v

∴            P = (ma× at = ma2t

As m and a are constants, therefore, P ∝ t
258 Views

What is watt?

SI unit of power is Watt. 
773 Views

Is work a scalar or a vector quantity?

Work is dot product of two vectors. i.e. F with rightwards arrow on top times S with rightwards arrow on top.

And dot product is a scalar quantity. Therefore, work is a scalar quantity. 
1450 Views

Define the unit joule.

Work done is said to be one joule if one newton of  force displaces the body through a distance of one meter in the direction of applied  force .
799 Views

What are different units of energy?

The different units of energy are :

(i) Joule            
(ii) Erg
(iii) eV            
(iv) KWh
(v) Calorie.

804 Views

Define watt.

Power is said to be one watt if one joule of work is done in one second. 
860 Views