Gravity Pitch Gizmo Answer Key

Name: Conor Mcdowell Date: 07-21-2022 Student Exploration: Gravity Pitch Directions: Follow the instructions to go through the simulation. Respond to the questions and prompts in the orange boxes. Vocabulary: escape velocity, gravity, orbit, orbital velocity, trajectory, velocity Prior Knowledge Questions (Do these BEFORE using the Gizmo.) On their summer vacation, a family is standing at a scenic overlook at the top of a tall cliff. Young Alice (age 2) tosses a rock over the edge and giggles as she watches it fall. Brother Darrell (age 8) thinks he can do better and hurls another rock over the edge. Papa Billy chuckles, picks up a nice round rock, and flings it off the cliff as hard as he can. 1. ✏️ In the picture to the right, draw the trajectory, or path, that each rock would take. Label the three trajectories “Alice”, “Darrell” and “Billy” (or just A, D and B). 2. What would happen if Billy could throw the rock as fast as a rocket? The rock would fall to the ground at the same time as the others despite traveling further. Gizmo Warm-up: Which way does gravity pull? 1. Use the slider to set the Velocity to 0.0 km/s (kilometers per second). Velocity is basically the same thing as speed, but has direction as well. In this case the pitcher is simply dropping the ball. Click Play ( ). A. What direction does the ball go? It descends directly. B. Sketch the pitcher and the trajectory of the ball on the diagram. 2. Click Reset ( ) and drag the pitcher to several new positions. Click Play and watch him drop the ball each time. Sketch the pitcher and the trajectory of each ball on the diagram. A. What do you notice? No matter where the pitcher is positioned, the ball will always fall directly. B. The ball is pulled by a force called gravity. In what direction does gravity always pull the ball? Objects are drawn towards the earth's surface by gravity. Get the Gizmo ready: Activity A: How far does it go? ● Click Reset. ● Drag the pitcher back to the top. ● Set the Velocity to 1.0 km/s (2,232 miles per hour). Question: Why do objects go around, or orbit, other objects? 1. Observe: Click Play and observe the ball’s trajectory. (Note: The pitcher is very tall – about 1500 km (930 miles) tall!) ✏️ 2. Predict: How would the trajectory of the ball change as the pitcher throws it harder and harder? Explain below, and draw several predicted trajectories on the diagram. The ball will continue to move further into the x-axis until gravity pulls it downward. 3. Collect data: Throw the ball at velocities of 3, 5, and 7 km/s. If necessary, use the Fast forward button ( ) to speed things up and the “–” zoom control to see a larger area. For each throw, sketch and label the trajectory and record the Distance traveled in the table below. Velocity 3 km/s 5 km/s 7 km/s Distance traveled 2,784 km 5,204 km 46,457 km 4. Analyze: What happens? The ball falls to the ground due to gravity and travels farther the faster it is thrown. 5. Draw conclusions: What force causes objects to stay in orbit? Gravity 6. Run Gizmo: Test 8 km/s and 9 km/s. (If you have a lot of spare time, try 10 km/s as well.) Use the “–” zoom control. What happens? Each test has its own orbit around the earth but always stops when it goes back to the pitcher with each orbit getting larger. Activity B: Comparing planets Get the Gizmo ready: ● Click Reset. ● On the Planet menu, choose Venus. ● Set the Velocity to 1 km/s. Question: How would the gravity of other planets affect a pitched ball? 1. Observe: Look at the Planet mass and Planet radius of Venus. The mass of a planet is how much matter it contains. The radius of a planet is the distance from the center to the surface. Compared to Earth, what are the mass and radius of Venus? Venus mass: 0.81 × Earth’s mass Venus radius: 0.95 × Earth’s radius 2. Predict: Will the pitcher have to throw the ball faster or not as fast to send a ball into orbit around Venus? not as quickly Why? Because Venus is smaller than Earth, it has a weaker gravitational attraction. 3. Run Gizmo: Orbital velocity is the velocity needed to make a circular orbit. Use the Gizmo to find the orbital velocity of the ball on Venus. Make the orbit as circular as you can. A. What is the orbital velocity on Venus? 6.5 kms B. Do the same on Earth. What is the orbital velocity on Earth? 7 kms C. Based on this, which planet do you think has stronger gravity, Venus or Earth? Explain Because of its faster orbital velocity, Earth has a stronger gravitational pull. 4. Predict: Select Mars. Estimate what the orbital velocity will be on Mars: Why did you choose that value? 3 kms Less than half of the earth's terminal velocity might be effective because mars is smaller than the earth. 5. Run Gizmo: Adjust the Velocity until you create a circular orbit on Mars. A. What is the orbital velocity on Mars? 3 kms B. How does gravity on Mars compare to Earth and Venus? Compared to the earth and venus, mars has less gravity. 6. Extend your thinking: The escape velocity is the smallest velocity needed for the baseball to escape from the planet’s gravity and fly off into space, never to return. When the ball reaches escape velocity, the Distance traveled will read “infinity.” A. Which planet do you think has the lowest escape velocity? Mars B. Use the Gizmo to test your prediction. Were you correct? Yes