Question

a hammer of mass 1kg falls freely from a height of 20m. Calculate velocity and kinetic energy​

Answer 1

QUESTION:-

A hammer of mass 1kg falls freely from a height of 20m. Calculate velocity and kinetic energy​

EXPLANATION:-

Let's calculate it's velocity

Using 3rd equation of motion:-

$\sf\:v^2=u^2+2gh\\\\\since\;u(initial\;velocity)\;is \;zero\;because\;the \;hammer\;falls\;from\;rest \\\\v^2=u^2+2gh\\\\v=\sqrt{2gh}$

So here h(height)=20 m

g=9.8 ms²

Let's apply thee given data in the formula to calculate final velocity

$\sf\:v=\sqrt{2gh} \\\\v=\sqrt{(2)(9.8)(20)} \\\\v=\sqrt{(40)(9.8)} \\\\v=\sqrt{392} \\\\v=17.79\;m\;s$

So the Velocity of the hammer  is =17.79 m s

Now let's calculate it's kinetic energy.

$\sf\:kintic\:energy=\frac{1}{2}(mass)\((velocity)^2\\\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;\;or\\\\k.e=\frac{1}{2}mv^2$

Mass of body=1 kg

Velocity of body=17.79 m s

$\sf\;k.e=\frac{1}{2}(1)(17.79)^2\\\\k.e=\frac{1}{2}(1)(316.48)\\\\k.e=(1)(158.24)\\\\k.e=158.24\;j$

Hence the kinetic energy of the hammer=158.24 j