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Class 10 Class 12

Consider a drop of rain water having mass 1 g falling from a height of 1 km. It hits the ground with a speed of 50 m/s. Take g constant with a value 10 m/s2. The work done by the (i) gravitational force and the (ii) resistive force of air is

• (i) – 10 J (ii) –8.25 J

• (i) 1.25 J (ii) –8.25 J

• (i) 100 J (ii) 8.75 J

• (i) 10 J (ii) –8.75 J

D.

(i) 10 J (ii) –8.75 J

wg+ wa= Kf– Ki

wa= –8.75 J i.e. work done due to air resistance and work done due to gravity = 10 J

wg+ wa= Kf– Ki

wa= –8.75 J i.e. work done due to air resistance and work done due to gravity = 10 J

4191 Views

Define watt.

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

Is work a scalar or a vector quantity?

Work is dot product of two vectors. i.e. .

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

What is watt?

SI unit of power is Watt.
773 Views