The relationship between speed, mass, weight, and friction was studied using a toy car that carried additional masses. The car was placed on a 1m inclined plane and released. The time it took to go down the incline and the time it took to go one meter beyond the incline were recorded.

Additional masses were added to the car as it was released down the incline plane. The car has a mass of 50 g. The plane was angled at a 25 degree angle.

**Experiment 1:**

Additional masses were added to the car as it was released down the incline plane. The car has a mass of 50 g. The plane was angled at a 25 degree angle.

Mass on Car |
Time Down Plane |
Time for Additional 1 Meter |

10g |
5.3 seconds |
4.8 seconds |

20g |
5.2 seconds |
5.7 seconds |

30g |
5.3 seconds |
6.6 seconds |

*The incline of the plane was changed to determine its effect on the time it took the car to travel down the plane. There were no additional masses placed on the car.*

**Experiment 2:**

incline of the plane |
Time Down Plane |
Time for Additional 1 Meter |

15 deg |
5.4 seconds |
4.9 seconds |

25 deg |
5.1 seconds |
4.7 seconds |

35 deg |
4.7 seconds |
4.4 seconds |

How is the design of Experiment 1 different from that of Experiment 2?

A. Experiment 2 varied the mass on the car while Experiment 1 varied the angle of the plane.

B. Experiment 1 varied the mass on the car while Experiment 2 varied the angle of the plane.

C. Experiment 1 and Experiment 2 tested the same variable in different ways.

D. Experiment 1 and Experiment 2 have no differences.

A. Experiment 2 varied the mass on the car while Experiment 1 varied the angle of the plane.

B. Experiment 1 varied the mass on the car while Experiment 2 varied the angle of the plane.

C. Experiment 1 and Experiment 2 tested the same variable in different ways.

D. Experiment 1 and Experiment 2 have no differences.

**Solution:**

In both charts, the independent variable is listed in the first column, and the dependent variables are listed in the second and third columns.

In Experiment 1, the independent variable is the mass of the car.

In Experiment 2, the independent variable is the angle of the plane.

**Choice B is the correct answer.**