If a vehicle with a mass of 1200 kg has a speed of 120 km/h, what is the vehicle's kinetic energy as determined by someone at rest alongside the vehicle's road?
2006-10-24 16:15:04 · 5 answers · asked by Anonymous in Science & Mathematics ➔ Physics
Kinetic Energy (KE) equals 1/2 the car's mass (m) multiplied by its speed (v) squared,
KE = 1/2 mv^2
m = 1200 kg
Must convert km/h to SI units of m/s,
v = 120 km/h = 120000 m/h = 33.33 m/s
KE = 1/2 (1200 kg) * (33.33 m/s)^2
KE = 6.66 E5 Joules
2006-10-24 16:23:27 · answer #1 · answered by mrjeffy321 7 · 0⤊ 0⤋
use
kinetic energy = 1/2 multiply by mass multiplied by the square of the speed
convert km /h to m/s
since energy is in joules
well that is how we canadians learn it
2006-10-24 23:22:18 · answer #2 · answered by Anonymous · 0⤊ 0⤋
The kinetic energy is 666.7 kilo Joules
KE = (0.5)*m*v^2
[(120 km/h)*(1000 m/1km)*(1 h/ 3600 sec)]^2 = 1111.1 m/sec
KE = (1111.1 m/sec)*1200 kg*0.5 = 666666.7 joules
2006-10-24 23:18:16 · answer #3 · answered by sman 2 · 0⤊ 0⤋
KE = 1/2 mv^2
make sure you are in the right units...i'm used to using speeds measured in m/s so:
120km/h *1000m/1km * 1hr/60min * 1min/60s = 33.3333m/s
so:
120km/h = 33.3333m/s
now sub in for the KE equation:
KE = (1/2)mv^2
KE = (1/2)(1200kg)(33.3333m/s)^2
KE = 666,665.3333 J
KE = 666.6653KJ
2006-10-24 23:50:18 · answer #4 · answered by Elfy 2 · 0⤊ 0⤋
1/2mass*velocity2.
2006-10-24 23:43:04 · answer #5 · answered by wildstar_2 6 · 0⤊ 0⤋