Shrek and Donkeyin

Pull the Cart you lazy Donkey!

• If I pull on you and you pull on me with the same force can we move?

Donkey

Yeah Shrek

the horse ran off and we need you to pull the cart

That thing looks heavy

Yeah, but can you do it?

I’ve been studying physics and..

Ya, what? What do you know about Physics?

Shows what you know, I am edumacated, and Newton’s 3rd law says that if I apply a force on the carriage, the carriage will apply an equal and opposite force on me. The forces will cancel out and we won’t move.

Lazy, silly Donkey, that is not how Newton’s Third Law works!

If Donkey pulls on the cart will the cart pull back on

him?

Is donkey right that the forces will cancel each

other out?

Let’s look at the forces on Donkey

Force of the ground pushing Donkey Forward

Force of the carriage pulling back on Donkey

As long as the force of the ground pushing Donkey is greater than the force of the carriage pulling back, donkey will move.

Let’s look at the forces on the Carriage

Force of the Donkey pulling forward

Force of the friction pushing back on Carriage

As long as the force of Donkey is greater than the force of friction, the carriage will move.

The Forces Don’t cancel each other out because

the are on different objects. one on the cart

and one on Donkey

Donkey will push on the ground and the ground will push back, allowing him to

move the cart

Ha Ha, Physics

triumphs!