# Friction

#### Friction: Investigation 1 - Frictional Force

In Investigation One, you will use a spring scale to measure frictional force. During this Investigation, you will:

1. Push a penny toward a goal line, observed its movement, and measured the distance it traveled.
2. Consider positive and negative acceleration as the penny moves.
3. Observe the magnitude of force as a woodblock is pulled across the bench with a spring scale.
4. Measure the frictional force between the woodblock and the table using a spring scale.
5. Calculate the average velocity of the woodblock using the following formula: 1. Calculate the sum of all forces using the following formula: #### Friction: Investigation 2 - Velocity and Frictional Force

In Investigation Two, you will test the influence of velocity on a frictional force. During this Investigation, you will:

1. Measure the force required to pull a woodblock 50 cm in the following time segments:
• 2 s
• 4 s
• 6 s
• 8 s
1. Calculate the average velocity for each trial using the following formula: #### Friction: Investigation 3 - Weight, Surface Area, and Frictional Force

In Investigation Three, you will investigate weight and surface area and how they affect frictional force. During this Investigation, you will:

1. Determine the mass of each of the following loads:
• Wood box
• Wood box and 100 g
• Wood box and 200 g
• Wood box and 300 g
1. Convert mass in grams to kilograms using the following formula: 1. Calculate the weight of each load using the following formula:
##### Weight (N) = mass (kg) × acceleration due to gravity (9.8 m/s2)
1. Measure force by pulling a woodblock on each of its (3) surfaces:
• Bottom
• Side
• End
1. Calculate the surface area of each of the surfaces on the woodblock by using the following formula:

Surface area (cm2) = length (cm) × width (cm)

#### Friction: Investigation 4 - Surface Type and Frictional Force

In Investigation Four, you will explore the frictional force of different types of surfaces. During this Investigation, you will:

1. Pull a woodblock 50 cm to measure the frictional force for surface combinations.
1. Measure the mass of the woodblock in grams using a triple beam balance.
2. Convert grams to kilograms using the following formula: 1. Calculate the coefficient of friction using the following formulas:

Weight (N) = mass (kg) × acceleration due to gravity (9.8 m/s2) 