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### Course: Physics archive>Unit 4

Lesson 1: Circular motion and centripetal acceleration

# Loop de loop question

Asks students to find the minimum speed necessary to complete the loop de loop. Created by Sal Khan.

## Want to join the conversation?

• does the average velocity change at every differnt time and place on the loop de loop?
• In a sense, yes because velocity includes direction. However, the magnitude should be the same. For example, if the car was going at say 50mph, and we said that straight up is positive and straight down is negative, than the velocity of the car on the far right of the circle would be +50mph, while the velocity of the car on the far left side would be -50mph. The velocities are thus different. However, the absolute values of + and - 50 are both 50. I have literally just forgotten the point of this. OH YEAH your original question! So yeah the velocity changes but when dealing with the equations in this section with those omegas and thetas and stuff, the velocity should be kept the same. So no? It's fine if you just use the same number throughout. Sorry I wrote so much. I'm bored.
• what would happen if he slammed the brakes while he was upside down?
• The car would probably fall
• Just wondering how to find the largest value the radius can have in order to complete the loop.
• Did Sal tell us what was the radius of the track ??
(1 vote)
• What would the energy of the car be at the top of the loop de loop?
(1 vote)
• When i make sonething move along aloop in space with some certain initial speed( which is not changed)is the speed while going through loop is constant(assuming it is not affected by any force)?
(1 vote)
• If there were multiple loop de loops together on say, a roller coaster, how would the moving roller coaster car be able to go at top speed on the tracks without falling off of the tracks?
(1 vote)
• What is the loop de loop?