Download Physics Chapter 6 Name: Lab: Tug of War Date: Purpose: Observe

Physics Chapter 6
Name:
Lab: Tug of War
Date:
Purpose: Observe net forces.
Procedure
Part 1
1. Obtain a 20 N spring scale and a kilogram mass. Attach a 30 cm. string to the
mass and the scale. In the hallway carpet, determine the maximum force one can
apply without moving the mass. Record this value. Repeat several times to have an
acceptable value.
Force Value:
2. Repeat the process except determine the force needed to move the kilogram
mass at a constant velocity. Repeat several times to have an acceptable value.
Force Value:
3. As the mass is moving, determine the force needed to accelerate the mass to a
greater velocity. Repeat several times to have an acceptable value.
Force Value:
Part 2
1. Each group needs a battery-powered car. Attach a 0.5 meter string to the car.
Attach a force scale to the string. Hold the scale and determine the force exerted by
the car as it tries to move away.
2. Pair up with another group. Attach a string between the two cars. Make the
string snug between the two cars. Turn each car on and observe a tug of war
between the cars. Explain the result of your tug of war in relation to the net force
and the measured force that each car exerts.
2. Repeat against another group’s car. Result?
Questions.
1. What is a net force?
2. Why is more force required to move the kilogram mass from rest than is used to
keep it moving at a constant velocity?
3. Why is more force needed to accelerate the mass?
4. Draw a motion diagram of the tug of war with the first car. Show force vectors on
each car.
5. Explain what will happen in the following force diagrams in a tug of war.
a.
b