A car is traveling with a velocity of 30 m/s has a kinetic energy of 800,000 J. What is the mass of the car?

1 Answer
Dec 18, 2015

Answer:

The mass of the car is 1800 kg.

Explanation:

Kinetic energy is the energy of motion. Anything that has motion has kinetic energy.

The equation for determining kinetic energy is #"KE"=1/2mv^2#, where #"KE"# is kinetic energy in J, #m# is mass in kg, and #v# is speed in m/s.

Given
#"KE=800000 J"="800000 kg·m"^2/"s"^2#
#v="30 m/s"#

Unknown
#m#

Solution
Rearrange the equation to isolate #m# and solve.

#"KE"=1/2mv^2#

#m=(2"KE")/(v^2)#

#m=(2·800000"kg·m"^2/"s"^2)/((30"m/s")^2"#

#m=(2·800000"kg·m"^2/"s"^2)/(900"m"^2/"s"^2)#

#m="1800kg"# (rounded to two significant figures)

http://academic.umf.maine.edu/magri/PUBLIC.acd/tools/SigFigsAndRounding.html