2007-01-01 14:44:07 · 6 answers · asked by Paul Foglino 1 in Science & Mathematics ➔ Physics
1/2M*v^2
convert lbs to kilograms and mph to meters/second
2007-01-01 14:48:52 · answer #1 · answered by j b 2 · 0⤊ 0⤋
with this answer round it off to your will
51489.985728632085449354801494868 joules
First i converted 30 mph to meters per sec and then I used algebra to find the mass with the equation F=ma in which in this case a is g gravity and gravity is 9.8m/s squared and F is lb i did this because pounds is a unit of force the force pushing you down then all i did was plug it in the equation for kinetic energy k=1/2 m v squared and i got this answer
2007-01-02 18:46:21 · answer #2 · answered by Hephaestus 2 · 0⤊ 0⤋
To answer, you just have to express mass in kg and velocity in m/s and use the formula E (J) = mV^2/2 when m and V are expressed in SI-Metric System.
For the example, 1mile = 1,609.3 metres
1pound = 0.454 kg
1 hour = 3,600 seconds
So, the mass is 2100x0.454 = 953.4 kg
the velocity is 30.0x1,609.3/3600 (m/s) = 13.411 (m/s)
And finally, the kinetic energy is
E = mV^2/2 = 953.4x(13.411)^2/2 (J) = 85,736.84 (J) =(approximately) = 85,740 Joules
2007-01-01 15:20:54 · answer #3 · answered by Oakes 2 · 0⤊ 0⤋
1/2(m)v^2=2100 1/2(m)(2v)^2=4x2100=8400 joules,m will NOT change much. God bless you.
2016-03-29 03:55:55 · answer #4 · answered by Anonymous · 0⤊ 0⤋
KE=1/2Mv^2
KE (joules)= (1/2 x mass of car (kg) x velocity of car (m/s) squared.
KE=.5 * 2100lb * (.45kg/lb) * (30 miles/hr * 5280 ft/mile * .3048 m/ft / (3600 sec/hr))^2 = ~84, 984 joules
2007-01-01 14:57:34 · answer #5 · answered by Big D in Norco, CA 2 · 0⤊ 0⤋
KE = 1/2 m v^2
You have to convert to the correct units. kg for the car, m/s for the velocity.
2007-01-01 14:48:04 · answer #6 · answered by daedgewood 4 · 0⤊ 0⤋