Hover Gliders

Hover Gliders

Objectives

• Analyze collisions between objects with the same mass. (Exploration 1)
• Analyze collisions between objects with different masses. (Exploration 2)
• Develop an understanding of momentum’s role in collisions. (Exploration 3)
• Compare and contrast collisions in which energy is conserved with collisions in which energy is lost. (Exploration 4)

Description of Activity

In this activity, you control a pair of hover gliders. There is no friction between the hover gliders and the ground, and the effects of air resistance are negligible. You can adjust the mass and the initial velocity of each hover glider as well as the amount of energy lost in any collision between the hover gliders. The Jump Start exercises below are designed to help you review concepts of mass, inertia, velocity, and momentum.

Jump Start

1. Compare and contrast inertia with momentum.

• Mass, as a quantitative and fundamental measure of inertia is resist change in its state of motion.
• Momentum is a vector quantity, and being the produce of a body’s inertial mass and it’s velocity
• Without an external force they cannot be changed.  
• They both exist at the exact moment that momentum’s current vector meets resistance and the impending inertia is established.  

1. Calculate the momentum of a 1250-kg car that is moving at 25 m/s north.

• p = mv =(1250kg) *(25m/s) = 31250 kg*m/s north

1. Which has more inertia: a stationary bowling ball or a rolling tennis ball? Which has more momentum? Explain. Which has more momentum: a stationary bowling ball or an identical rolling bowling ball?

• The stationary bowling ball has more inertia because bowling ball has more mass than the tennis ball. However the rolling tennis has more momentum than the stationary bowling ball. The momentum for the bowing ball is 0, yet the momentum for the tennis is greater than 0.

1. Does the momentum of a pencil change as it falls? Explain.

• Yes, the momentum of a pencil changes as it falls. Because p (momentum)=mv, the momentum of the pencil before the fall is p=m*v(0)=0, the momentum of the pencil during the fall is p =m*v (9.8 m/s).

1. Carla and Irene walk toward each other. Both are moving at 5 m/s and both have a mass of 50 kg. Do they have equal momenta? Explain.

• No, they don’t have equal momenta, because they are opposite in directions. Momentum is a vector quantity.  

Exploration 1: Collisions Between Two Gliders with Equal Mass

Procedure

1. Explore the simulation on your own for several minutes. Search for relationships between the velocities and momenta before and after the collision.
2. Set Mass to 1.00 kg for both hover gliders. Set Initial velocity of glider 1 to 2.00 m/s. Set Initial velocity of glider 2 to −2.00 m/s. Set Energy lost from collision to 0.00 J.
3. Select Go. Record the hover gliders’ final velocities in Table 1 below.  
4. Select Restart. Repeat steps 1–3 eight more times, but change the initial velocities each time to match the values shown in Table 1. Observe the gliders’ motion each time, and record the final velocities in Table 1. Keep Mass at 1.00 kg for both hover gliders
   and Energy lost from collision at 0.00 J    

Observations and Analysis

Table 1 (masses of both gliders = 1.00 kg; energy loss = 0.00 J)

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