In this lesson you will:
use your observation and investigative skills to explore a Physics simulation on gravity and orbits.
undertake an investigation on one variable of the Law of Universal Gravitation.
Learning Intentions:
To know that everything with a mass has gravity and that the larger the mass the larger the force of gravity.
To understand that it’s gravity that causes objects in space to travel in orbits (circular paths).
To be able to conduct a scientific investigation to identify the effect of mass of a celestial object on orbit time.
Success Criteria:
I can use my observation and investigative skills to answer questions on a gravity and orbit simulation.
I have successfully developed a scientific procedure to investigate the effect of a variable on orbit time
Some of the activities in this lesson are must do activities. These are also called a mini challenge. Please have a go at the should do activities and reach out to your teacher if you need assistance. You could also spend some extra time problem solving a solution to these challenges. Finally, there are super challenge activities, the could do activities. We strongly encourage you to try these.
Read the passage carefully.
Within the pages of Principia (the book that made him famous), Newton presented his law of universal gravitation as a case study of his laws of motion. All matter exerts a force, which he called gravity, that pulls all other matter towards its centre. The strength of the force depends on the mass of the object: for example, the Sun has more gravity than Earth, which in turn, has more gravity than an apple. Also, the force weakens with distance.
Newton’s laws of motion and gravity explained Earth’s annual journey around the Sun. Earth would move straight forward through the universe, but the Sun exerts a constant pull on our planet. This force bends Earth’s path toward the Sun, pulling the planet into an elliptical (almost circular) orbit.
Gravity is a “built-in” property of mass. Wherever there are masses in the universe, they will interact via the force of gravitational attraction. The more mass there is, the greater the force of attraction. Here on Earth, the largest concentration of mass is, of course, the planet we stand on, and its pull dominates the gravitational interactions we experience. But everything with mass attracts everything else with mass anywhere in the universe.
Newton’s law also implies that gravity never becomes zero. It quickly gets weaker with distance, but it continues to act to some degree no matter how far away you get. The pull of the Sun is stronger at Mercury than at Pluto, but it can be felt far beyond Pluto, where astronomers have good evidence that it continuously makes enormous numbers of smaller icy bodies move around huge orbits.
Complete the following in your exercise book or folder.
List 3 facts.
Write down 2 things you found interesting.
Record 1 question you have about what you just read.
To complete the following tasks use the embedded simulation below.
The picture here should help with navigating and using the simulation.
Start by selecting the To Scale option.
Complete the following in your exercise book or folder.
Predict what happens to the Earth’s orbit if the Sun’s mass is doubled.
Find three ways to change the number of days it takes the Earth to complete one revolution around the sun (a year). Record your answers.
Go back to the simulation and select the Model option.
First have a play by testing everything out.
Then design an experiment, by changing one variable in the simulation, to determine the effect of this variable on time of one complete orbit (in Earth days).
To get you started you could change the suns mass (but keep the other variable constant).
Complete the scientific investigation worksheet to the right. Select the button and then select Use Template to make a copy for yourself.
If you can't make a copy of the file, you can look at the template and copy the headings into your exercise book or folder and then write the report out by hand.
Don't forget to hand in the work you completed today!
Your teacher will have told you to do one of the following:
Upload any digital documents you created and any photos you took of your written work to your Learning Management system (MS Teams, Google Classroom for example).
Email any digital documents you created and any photos you took of your written work to your teacher.
Make sure you keep any hand written work you did in your exercise book or folder as your teacher may need to see these when you are back in class.