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Matter In Our Surroundings

Question
CBSEENSC9006300
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In each of the following a force F is acting on an object of mass m. The direction of displacements is from west to east shown by the longer arrow. Observe the diagrams carefully and state whether the work done by the force F is negative, positive or zero.

 

 

Solution

Given, 
Force is acting on an object of mass m.
(a) We have,

Force is perpendicular to displacement,
            straight W space equals space Fs space cos space 90 degree space equals space 0 space
(b) Here, Force and displacement are in the same direction.
                   
           straight W space equals space Fs space Cos space 0 degree space equals space Fs space equals space straight a space positive space work.
(c) In this case, Force and s are in opposite direction. 
Therefore, 
straight W space equals space Fs space cos space 180 degree space space space space space space equals space Fs left parenthesis negative 1 right parenthesis space space space space space space equals space minus Fs space comma space straight a space negative space work.

Some More Questions From Matter In Our Surroundings Chapter

Convert the following temperature to Celsius scale.

300K

Convert the following temperature to Celsius scale.

573 K

Convert the following temperatures to Kelvin scale

25°C

What is the physical state of water at

100 °C

For any substance, why does the temperature remain constant during the change of state ?

Suggest a method to liquify atmospheric gases.

Convert the following temperatures to Kelvin scale.

35°C

Give reason for the following observations.

Naphthalene balls disappear with time without leaving any solid.

Give reason for the following observations.

We can get the smell of perfume sitting several metres away.

What is the physical state of water at

a) 25°C
b)00C
c)1000C

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