Question

The tractor is moving with velocity of 6km/hr. Mass of belt is 720gm .KE of belt is

Answer 1

Answer:

The kinetic energy of belt is 1 J.

Explanation:

Given that,

Velocity of tractor = 6 km/h

Mass of the belt = 720 gm

Kinetic energy :

The kinetic energy is the half of the product of mass and square of velocity.

We need to calculate the kinetic energy

Using formula of K.E

$K.E=\dfrac{1}{2}mv^2$

Put the value into the formula

$K.E=\dfrac{1}{2}\times720\times10^{-3}\times(6\times\dfrac{5}{18})^2$

$K.E=1\ J$

Hence, The kinetic energy of belt is 1 J.

Answer 2

Answer:

The above answer is wrong

Explanation:

The lower part is attached with the ground right as it is tractor. So there will not be any slipping,

So the velocity of the lower part is zero and hence no kinetic energy

The part of belt attached to wheel can be neglected because it is very less compared to other portions

So we can say half of the mass is on the lower part and half is on upper part

Since the lower part have kinetic energy zero

We need to find the kinetic energy of upper part only using the very simple equation 1/2 m v2

Look at the above image

There top portion have twice the velocity

How we got 2v right??

Check the second img