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Title: Down the Ramp
CSCS:
Principle(s) Investigated: As mass increases, so does potential energy (Ug = mgh)
HS-PS2-1
Analyze data to support the claim that Newton’s second law of motion describes the mathematical relationship among the net force on a macroscopic object, its mass, and its acceleration. [Clarification Statement: Examples of data could include tables or graphs of position or velocity as a function of time for objects subject to a net unbalanced force, such as a falling object, an object rolling down a ramp, or a moving object being pulled by a constant force.] [Assessment Boundary: Assessment is limited to one-dimensional motion and to macroscopic objects moving at non-relativistic speeds.]
Materials:
- Dynamics Trolley Carts or other Vehicles
- Stopwatch or Smartphone Stopwatch
- 0.50-kg mass
- 1.0-kg mass
- Board/Ramp
- Textbooks or other Ramp Supports
- Additional masses (optional)
- Meterstick (optional)
- Protractor (optional)
Procedure:
The teacher demonstrates an unloaded vehicle traveling down the ramp while students time.
Students are ask to predict what will happen to the time when the weight is added to the vehicle.
Students break into groups and take data on the same experiment with different weights using CSCS.
The class data is analyzed and students are asked to identify a trend.
Students are asked to predict future results using the trend.
Students are asked to draw from prior knowledge and propose an equation or set of equations that might describe the trend.
Student prior knowledge
- Acceleration due to gravity
- Friction
- Potential Energy
- Kinetic Energy
Questions:
Did the speed at the bottom of the ramp depend on the mass of the cart/vehicle?
Compare the gravitational potential energy of the cart/vehicle at the starting position to the kinetic energy along the floor.
List and explain the equations you used to find energy. What do the equations suggest about the speed at the bottom when the mass is changed?
Applications to Everyday Life:
This explains truck breaking systems and the need for runaway truck ramps. The more massive a truck the more energy it has when going downhill.
This activity could be an introduction for an engineering lesson on building racing vehicles. Sports that rely on gravity will benefit from heavier vehicle design such as bobsled and luge, while sports that require flat or uphill thrusts will suffer from added weight.
High school students could use this to build or choose a skate ramp, matched to their personal potential energy.
Photographs:
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