How Circular Motion Changes
Changing one value at a time
- When one value changes, first state which other values stay fixed.
- Keep m and r fixed. Doubling v makes F four times as large.
- Keep m and v fixed. Doubling r makes F half as large.
- Keep m and fixed. Doubling r makes F twice as large because the speed also increases.
Circular Motion Explorer
Move one slider at a time. The diagram and numbers change at the same time. The red and green arrow lengths show different quantities. Do not compare them with each other. Compare one arrow before and after you move a slider.
Swipe left or right to see the whole diagram →
- Keep angular speed fixed. Increasing r increases both v and a.
- The equations for a and F contain angular speed squared. If angular speed doubles, a and F become four times their original values.
- Keep r and angular speed fixed. Changing m changes F only. It does not change v or a.
- Move only the mass slider. The speed and acceleration do not change. The force changes in direct proportion to mass.
- Move only the angular-speed slider. Compare the old and new values of v, a and F.
- Move only the radius slider while angular speed stays fixed. The speed, acceleration and force all increase.
Common mistake
Do not use the statement “a larger radius gives a smaller force” without stating what stays fixed. It is true when speed stays fixed. It is not true when angular speed stays fixed.