# What is the mass of the car?

1. Feb 2, 2005

### Lovely

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?

Last edited: Feb 2, 2005
2. Feb 2, 2005

### Sirus

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

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.

3. Feb 2, 2005

### Staff: Mentor

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.

4. Feb 2, 2005

### dextercioby

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.

5. Feb 2, 2005

### Lovely

the equation is KE=1/2mv(squared)

6. Feb 2, 2005

### Lovely

If I take these steps will I be able to find the mass of the car?

7. Feb 2, 2005

### dextercioby

Provided u work correctly,of course...

Daniel.