Certain force acting on a 20 kg mass changes its velocity from 5 ms^-1 to 2 ms^-1. Calculate the work done by the force.

Solution

Given,

Mass, m = 20 kg
Initial velocity, u= 5 ms^-1
Final velocity, v= 2 ms^-1Work done = change in K. E.

W = $\frac{1}{2}$ mv² - $\frac{1}{2}$ mu²

= $\frac{1}{2}$ m ( v²- u²)

= $\frac{1}{2}$ x 20 x (2² - 5²)

= 10 (4-25)

= -10 x 21

= -210 J

Here, the negative sign implies the retarding nature of the applied force.

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Certain force acting on a 20 kg mass changes its velocity from 5 ms^-1 to 2 ms^-1. Calculate the work done by the force.

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Certain force acting on a 20 kg mass changes its velocity from 5 ms-1 to 2 ms-1. Calculate the work done by the force.

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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.

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What is the physical state of water ata) 25°C b)00Cc)1000C

What is the physical state of water at0°C

What is the physical state of water at100°C

Give two reasons to justifyWater at room temperature is a liquid.

Give two reasons to justifyAn iron almirah is a solid at room temperature.

Why is ice at 273K more effective in cooling than water at the same temperature ?

Mock Test Series

NCERT Sample Papers

Entrance Exams Preparation

Certain force acting on a 20 kg mass changes its velocity from 5 ms^-1 to 2 ms^-1. Calculate the work done by the force.

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

What is the physical state of water at
0°C

What is the physical state of water at
100°C

Give two reasons to justify
Water at room temperature is a liquid.

Give two reasons to justify
An iron almirah is a solid at room temperature.