- Trending Categories
- Data Structure
- Networking
- RDBMS
- Operating System
- Java
- MS Excel
- iOS
- HTML
- CSS
- Android
- Python
- C Programming
- C++
- C#
- MongoDB
- MySQL
- Javascript
- PHP
- Physics
- Chemistry
- Biology
- Mathematics
- English
- Economics
- Psychology
- Social Studies
- Fashion Studies
- Legal Studies

- Selected Reading
- UPSC IAS Exams Notes
- Developer's Best Practices
- Questions and Answers
- Effective Resume Writing
- HR Interview Questions
- Computer Glossary
- Who is Who

# Calculate the work done by the brakes of a car of mass $1000\ kg$ when its speed is reduced from $20\ m/s$ to $10\ m/s$?

Here given, the mass of the car $m=1000\ kg$

Initial velocity of the car $v_1=20\ m/s$

Final velocity of the car $v_2=10\ m/s$

Therefore, work done by the brake to reduce the speed will be equal to the change in kinetic energy of the car.

Therefore, $W=K_1-K_2$

$=\frac{1}{2}mv_1^2-\frac{1}{2}mv_2^2$

$=\frac{1}{2}m(v_1^2-v_2^2)$

$=\frac{1}{2}\times1000(20^2-10^2)$

$=\frac{1}{2}\times1000(400-100)$

$=\frac{1}{2}\times1000\times300$

$=1.5\times10^5\ J$

Therefore, work done by the brakes will be $1.5\times10^5\ J$.

Advertisements