# What is the mass of the car?

An automobile traveling 25km/hour has kinetic energy equal to 1*10(6 power)J
all i know is KE=mass*km/hour
What is the mass of the car?

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$$E_{K}=\frac{1}{2}mv^{2}$$

Isolate mass in this equation and substitute the information you have for the other variables. Remember that for kinetic energy to be in joules, mass must be in kilograms and velocity in meters per second.

Doc Al
Mentor
Lovely said:
all i know is KE=mass*km/hour
No, KE = $1/2 m v^2$. (Momentum is mass x speed; kinetic energy is a different thing altogether.) Be sure to use standard units: convert km/hour to m/s; mass will be in kg.

dextercioby
Homework Helper
Lovely said:
An automobile traveling 25km/hour has kinetic energy equal to 1*10(6 power)J
all i know is KE=mass*km/hour
What is the mass of the car?

To add a little bit,the thing i underlined it is completely incorrect,because u have multiplied a unit with a physical quantity and got another physical quantity...That cannot be true... Daniel.

dextercioby said:
To add a little bit,the thing i underlined it is completely incorrect,because u have multiplied a unit with a physical quantity and got another physical quantity...That cannot be true... Daniel.
the equation is KE=1/2mv(squared)

Doc Al said:
No, KE = $1/2 m v^2$. (Momentum is mass x speed; kinetic energy is a different thing altogether.) Be sure to use standard units: convert km/hour to m/s; mass will be in kg.
If I take these steps will I be able to find the mass of the car?

dextercioby