Question

A car moves at a speed of 50 kilometers/hour. Its kinetic energy is 400 joules. If the same car moves at a speed of 100 kilometers/hour, then its kinetic energy will be 800 1,600 3,200 4,500 joules.

Answer 1

800 joules because it's twice the amount

Answer 2

Answer:

If the same car moves at a speed of 100 kilometers/hour, its new kinetic energy will be 1600 Joules.

Explanation:

Kinetic energy is defined as energy of a body due to its motion.

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

Where:

v = Velocity of the body in m/s.

m = Mass of the body

Given:

v = 50 km/h= $\frac{50 \times 1000m}{3600 s}=13.8 m/s$

1 km = 1000 m

1 hour = 3600 seconds

Kinetic energy of the body,K.E = 400 Joules

Mass of the body = ?

$400 J=\frac{1}{2}m(13.8)^2$

$m=\frac{2\times 400 J}{(13.8 m/s^)2}=4.1465 kg$

If the same car moves at a speed of 100 kilometers/hour, then its kinetic energy will be K.E'

New velocity of the car = v'=100 km/h =

= $\frac{100 \times 1000m}{36 s}=27.77 m/s$

$K.E=\frac{1}{2}\times 4.1465 kg\times (27.77 m/s)^2=1 1600 joules$

If the same car moves at a speed of 100 kilometers/hour, its new kinetic energy will be 1600 Joules.