Question

Define Kinetic energy. Deduce the expression for the Kinetic Energy of a body.

If $V = 3 i + 4 j + 5 k$ is the instantaneous velocity of a body of mass $1.50 kg$ , calculate its Kinetic energy.

Accepted Answer

Kinetic energy is defined as the energy possessed by a body by the virtue of its motion. Kinetic energy is a scalar quantity.

Consider a body of mass $m$ at rest. To move the body the work $W$ is done by a force $F$ so that the body covers a distance $s$ .

$W = F \times s W = (m a) s - - - (i)$

When the work is done, the velocity of the body changes from $u$ to $v$ and the body moves at an acceleration $a$

According to the third equation of motion,

$v^{2} - u^{2} = 2 a s s = \frac{v^{2} - u^{2}}{2 a}$

Putting the value of $s$ in equation $V = 3 i + 4 j + 5 k$ ,

$W = m a \times \frac{v^{2} - u^{2}}{2 a} W = \frac{1}{2} m v^{2} (∵ u = 0) ∴ K . E . = \frac{1}{2} m v^{2}$

Given: $V = 3 i + 4 j + 5 k$ , $m = 1.5 kg$

Magnitude of velocity = $\sqrt{3^{2} + 4^{2} + 5^{2}}$

$\Rightarrow \sqrt{50} = 5 \sqrt{2} m / s$

We know that $K . E . = \frac{1}{2} m v^{2}$

Putting the values in the above formula,

$\frac{1}{2} \times 1.5 \times {(5 \sqrt{2})}^{2} \Rightarrow 37.5 J$

Define Kinetic energy. Deduce the expression for the Kinetic Energy of a body.

If $V = 3 i + 4 j + 5 k$ is the instantaneous velocity of a body of mass $1.50 kg$ , calculate its Kinetic energy.

Important Questions on Board of Intermediate Physics I Year Model Question Paper (w.e.f. 2012-13)

Learn and Prepare for any exam you want !

Define Kinetic energy. Deduce the expression for the Kinetic Energy of a body. If V = 3i + 4j + 5k is the instantaneous velocity of a body of mass 1.50 kg, calculate its Kinetic energy.

Important Questions on Board of Intermediate Physics I Year Model Question Paper (w.e.f. 2012-13)

Learn and Prepare for any exam you want !

Define Kinetic energy. Deduce the expression for the Kinetic Energy of a body.

If $V = 3 i + 4 j + 5 k$ is the instantaneous velocity of a body of mass $1.50 kg$ , calculate its Kinetic energy.