Question

Calculate the kinetic energy of a car of mass 150kg moving with velocity of 30km/h. What will be the kinetic energy when it's velocity is doubled and then tripled?

Answer 1

$\huge\mathbb\red{ANSWER}$

GIVEN

mass of car(m) = 150 kg

velocity (v) = 30km/h

To Find

K.E of car

also when v is double and tripled

$\huge\color{brown}{ke=\frac{1}{2}m{v}^{2}}$

Now ke at given velocity is

$ke \: = \: \frac{1}{2} \: 150 \times {30}^{2} \\ \\ ke = \frac{1}{2}150 \times 900 \\ \\ ke = 30 \times 900 \\ \\ ke = 27000kj$

so when velocity is doubled

as we know

$ke \: \alpha \: {v}^{2} \\ \\ then \: if \: {v}^{2} is \: increased \: by \: 2 \: then \: ke \: is \: increased \: by \: 2 \: aslo \: \\ \\ then \: 2 {v}^{2} = 2ke \\ \\ 2(27000) \\ \\ so \: ke \: when \: velocity \: is \: 2times \: = 54000kj$

Now when velocity is tripled

$similarly \: ke \: \alpha \: {v}^{2} \\ \\ then \: 3 {v}^{2} \alpha \: 3ke \\ \\ then \: 3(27000) \\ \\ ke \: when \: velocity \: is \: 3times \: = 81000kj$

$\huge\mathbb\</strong><strong>g</strong><strong>r</strong><strong>e</strong><strong>e</strong><strong>n</strong><strong>{</strong><strong>EXPL</strong><strong>ANATION</strong><strong>}$

• 1st we find normal ke at normal velocity which is given is Question

• Now as we know that kinetic energy is directly proportional to square of velocity

• so ie as ke increases velocity increases

• bybusing above property we could find when velocity is doubled or triples

$\huge\mathbb\pink{EXTRAINFO}$

kinetic energy :- it is energy posses by body due to virtue of motion

when m is constant then kinetic energy is directly proportional to square of velocity

#here ke = kinetic energy

#and \alpha means directly proportional

hope it helps you

be brainly