MODEL ROCKET ------- Interactive Physics Simulation ------- Page 01
How high will your model rocket fly? At liftoff, the rocket engine is ignited and a thrust force is generated. The rocket accelerates upward for as long as it has fuel. At some point the rocket runs out of fuel and the engine shuts off. The rocket continues upward after the engine shuts off, but is now slowing down. Without a parachute, the rocket would likely be destroyed on impact. While accelerating upward, the thrust force exceeds the force of gravity on the rocket. When the rocket shuts off, the rocket continues moving upward while accelerating downward. Eventually, the downward acceleration brings the rocket to a stop, and it begins to fall. To access this physics simulation visit: http://goo.gl/jnehjx Page 02
Rocket Mass - This slider adjusts the mass of the rocket. A rocket with more mass will experience lower acceleration during launch for a given amount of thrust. Rocket Burn Time - This slider adjusts the amount of time the rocket 'burns' for before it shuts off. Longer burn times will lead to greater speeds as the acceleration of the rocket continues as long as the rocket burns. Rocket Thrust - This slider adjusts the amount of thrust applied by the rocket while it is burning. We're making the assumption that this thrust is constant in value over the burn time, and then immediately drops to zero. The amount by which the thrust exceeds the weight of the rocket determines the acceleration of the rocket. To access this physics simulation visit: http://goo.gl/jnehjx Page 03
Velocity Vs. Time - This is a plot of the velocity of the rocket as a function of time. Positive velocities are upward; negative velocities are downward. The slope of this graph represents the acceleration of the rocket - steeper graphs mean higher accelerations. When the velocity and slope are positive, the rocket is speeding up. When the velocity is positive but the slope is negative, the rocket is slowing down. When the line crosses zero, that means the rocket has stopped (momentarily) at the highest point in its motion. The area bounded by the triangular shape of this curve is equal to the height of the rocket above the ground. Altitude Vs. Time - This is a plot of the altitude of the rocket as a function of time. The slope of this graph is equal to the velocity of the rocket at any point in time. At its highest point, the slope is zero - this is the moment the rocket briefly stops and begins to fall back down. To access this physics simulation visit: http://goo.gl/jnehjx Page 04
What is the minimum rocket thrust necessary to accelerate a rocket with a mass of 0.6 kg and a burn time of 1.1 s? (Set the rocket mass slider to 0.6 kg and the rocket burn slider to 1.1 s. Then, adjust the rocket thrust slider and press play until the rocket experiences a change in velocity, as shown on the velocity-time graph.) Adjust the sliders to maximize the height of the rocket above the ground. (The area bounded by the triangular shape of the velocity-time graph is equal to the height of the rocket above the ground.) Adjust the sliders so that the rocket reaches its highest point (and stops momentarily) at t=2 seconds. (The rocket has momentarily stopped at its highest point in motion when the line of the velocity-time graph crosses zero.) To access this physics simulation visit: http://goo.gl/jnehjx Page 05
Challenge ME! Immediately after the rocket turns off, does the rocket continue moving upward or downward? What is the direction of the acceleration vector before and after the rocket turns off? What combination of thrust & rocket time will allow you to reach a maximum height of X? Need Help? Check out the Model Rocket Walkthrough video at: https://youtu.be/6a77galfxei To access this physics simulation visit: http://goo.gl/jnehjx Page 06
Do real spaceships fly straight up? No! Though it is important for them to gain altitude to get to a point where air drag is essentially absent, they also need to gain a lot of speed parallel to the Earth's surface in order to achieve orbit. If real spaceships flew straight up, they'd come right back down! What would it feel like when the rocket turns off? Just like an astronaut in space, you'd feel 'weightless' i.e., you'd feel like you were falling, even though you were still moving upward! How does dancing water fountain work? Once the water comes out of the ground, it is in free-fall, just like the rocket. It is still moving upward but accelerating downward. The water is accelerated in the pipes below the surface of the play area. Why do skydivers reach terminal velocity? When a skydiver first exits the plane, they accelerate towards the ground under the influence of gravity. They pick up speed very quickly. As their speed increases, they collide more and more forcefully with the molecules that make up the air. These collisions exert an upward force on the skydiver. As long as the downward force of gravity exceeds this upward force, the skydiver will keep speeding up. Eventually, the upward and downward forces balance, and the skydiver no longer speeds up - she reaches terminal velocity and moves at constant speed until she deploys her parachute. To access this physics simulation visit: http://goo.gl/jnehjx Page 07
Physics Concepts Click on the link below to learn more. Acceleration Due to Gravity - http://www.ck12.org/physics/acceleration-due-to-gravity Motion - http://www.ck12.org/physics/motion Acceleration - http://www.ck12.org/physics/acceleration Displacement During Uniform Acceleration - http://www.ck12.org/physics/displacement-during-uniform-acceleration Graphing Motion - http://www.ck12.org/physics/graphing-motion Velocity and Acceleration - http://www.ck12.org/physics/velocity-and-acceleration To access this physics simulation visit: http://goo.gl/jnehjx Page 08