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# Tag Archives: retarding force

## A Numerical from Kinematics

Advait Asks:

“A test projectile is fired horizontally into a viscous liquid with a velocity u.The retarding force is propotional to the square of the velocity, so that the acceleration becomes a=-k(v)^2 .v is the velocity at that point. Derive expressions for the distance D travelled in the liquid and corresponding time t required to reduce the velocity to u/2.

Neglect any vertical Â motion”

CAN YOU ANSWER?

## A question from Kinetic energy

Atul asked:

A lorry and a car moving with the same KE are brought to rest having same retarding force .which one of them should come at rest at shorter distance.

Ans:

According to Work Kinetic Energy theorem

Both should stop travelling the same distance

(This was a quick answer without a deep thought. If the readers have a diffrent opinion, please comment)