Question

find the increase in the kinetic energy of abody of mass 750g, when its velocity increases from 11m/s to 15 m/s​

Answer 1

GiveN :-

• The velocity of a body increses from 11m/s to 15m/s.
• The mass of the body is 750 g .

To FinD :-

• The increase in the Kinetic Energy.

SolutioN :-

Given that a body increases its velocity from 11m/s to 15m/s . We need to find the change in the Kinetic Energy . We know that kinetic energy is half the product of sqaure of velocity and mass.

$\red{\bigstar}\underline{\textsf{According to Formula of Kinetic Energy :- }}$

$\sf\dashrightarrow \pink{ Kinetic \ Energy =\dfrac{1}{2} mv^2 }\\\\\sf\dashrightarrow \Delta K.E. = \dfrac{1}{2}\times mv_1^2- \dfrac{1}{2}\times mv_2^2 \\\\\sf\dashrightarrow \Delta K.E. = \dfrac{1}{2} m ( v_1^2-v_2^2) \\\\\sf\dashrightarrow \Delta K.E . = \dfrac{1}{2}\times m \{ ( v_1+v_2)(v_1-v_2)\} \\\\\sf\dashrightarrow \Delta K.E. = \dfrac{1}{2}\times \dfrac{750}{1000} kg \{ (15+11)(15-11) \} \\\\\sf\dashrightarrow \Delta K.E . = \dfrac{0.75}{2}\times 26 \times 4\\\\\sf\dashrightarrow \Delta K.E . = 0.75 \times 13 \times 4 \\\\\sf\dashrightarrow\underset{\blue{\sf Required\ Answer }}{\underbrace{\boxed{\pink{\frak{ \Delta K.E . = 39 \ Joules }}}}}$

Also this is the work done. According to Work Energy Theorem the work done is equal to the Change in Kinetic Energy .