Advertisements
Advertisements
प्रश्न
A man carrying a suitcase in his hand is walking horizontally. What is the work done against gravity?
उत्तर
The displacement of the man and suitcase is along the horizontal direction. Thus, the angle between the displacement and the force of gravity is 90°;
Thus, W = Fd cos 90° = 0
Hence, no work is done against gravity in this case.
APPEARS IN
संबंधित प्रश्न
State the SI unit of work.
Is work a scalar or a vector quantity?
What is the condition for a force to do work on a body?
Fill in the blank with suitable word :
Work is measured as a product of __________ and __________
Is it possible that a force is acting on a body but still the work done is zero? Explain giving one example.
Name the physical quantity whose SI unit is Nm.
Is power a scalar quantity?
Complete the following sentences:
Kilowatt is the unit of ....... and kWh is the unit of
Complete the following sentences:
Joule is the unit of .......
A 100 W electric lamp emits energy in the form of light at the rate 10 J per second. What percentage of electric energy does the lamp transform into light energy?
If an electric bulb of 100 watt is lighted for 2 hours, how much electric energy would be consumed?
Fill in the boxe to show the corresponding energy transformation.
Give an example
Chemical energy changes to heat energy.
What do you understand by the term energy? Is energy a scalar or vector? How is the energy possessed by a body measured?
A girl of mass 40 kg runs a height of 80 stairs, each 25 cm high with a load of 20 kg on her head in 25 sec. If g is 10 m/s2, find:
(i) Gravitational force acting on the girl.
(ii) Work done by her.
(iii) Useful work done by her.
(iv) Her power in watt.
An electric motor pump is 60% efficient and is rated 2.5 H.P. Calculate the maximum load it can lift through a height of 10m in 8 sec. (1 H.P. = 750 W).
A force can cause an object to change its ______.
