Question

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Answer 1

Given:-

→ Mass of the body = 500kg

→ Initial speed of the body = 5m/s

→ Final speed of the ball = 3m/s

To find:-

→ Change in Kinetic energy of the body

Solution:-

Let the initial speed of the body be v₁ and the final speed of the body be v₂.

• K.E. = 1/2mv²

Thus, change in K.E. will be:-

= 1/2mv₂² - 1/2mv₁²

= m/2( v₂² - v₁² )

= 500/2[ (3)² - (5)² ]

= 250[ 9 - 25 ]

= 250[ -16 ]

= - 4000 J

[ Here, -ve sign represents that K.E. gets reduced by 4000 J ]

Thus, the decrease in kinetic energy of the body is 4000 J.

Some Extra Information:-

• Kinetic energy is the energy possessed by a body because of it's motion.

• K.E. = 1/2mv²

This expression shows that kinetic energy of a body depends on two factors.

(a) Mass [K.E ∝ m]

(b) Velocity [K.E. ∝ v² ]