Question

A car is moving with a speed of 15km/h and another identical car is moving with a speed of30 km/h. Compare their K.E

Answer 1

Explanation:

Apply for each the formula KE=1/2 (mv^2)

m will be cancelled and you will get the answer. Be sure to convert it into SI units to get answer in Joule.

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Answer 2

Answer:

KE1/ KE2 = 1 / 4

Explanation:

Given,

A car moves with a speed of 15km h-1 and another identical car is moving with the speed of 30 km h-1.

To solve: Compare K.E of cars

Solution:

Since, the cars are identical, it means there masses are same i.e mass of car 1 = mass of car 2. = m (say)

For car 1:

K.E1 =  1/2 mv² = (15)²m/2 = 225m/2

For car 2:

K.E2 = 1/2mv² = (30)²m/2 = 900m/2 = 450m

Now,

Ratio of their kinetic energy = KE1 / KE2 = 225m/2*450m = 1 / 4

therefore, K.E1 / KE2 = 1 / 4

i.e Kinetic energy or car 2 is 4 times the kinetic energy of car 1.