an open cart is moving along a straight frictionless horizontal track. When rain starts falling vertically into the cart, what happens to the speed of the cart?

The track is frictionless, so we can consider the cart as isolated system (no external forces acting on it): therefore, the momentum of the cart is conserved

[tex]p=mv=const.[/tex]

where m is the mass and v the speed of the cart.

When it starts raining, some water falls into the cart: this means that the mass of the cart, m, increases. But we said that the momentum, p, must remain constant: in order for that to happen, this means that the speed of the cart, v, must decrease (because the relationship [tex]mv=const.[/tex] is an inverse relationship, so if m increases, v must decrease).

alexanderchazdon alexanderchazdon · Answer 2 · 2020-12-02T18:06:46+01:00

Answer:

The speed of the cart decreases

Explanation:

The track is frictionless, so we can consider the cart as isolated system (no external forces acting on it): therefore, the momentum of the cart is conserved.

When it starts raining, some water falls into the cart: this means that the mass of the cart, m, increases. But we said that the momentum, p, must remain constant: in order for that to happen, this means that the speed of the cart, v, must decrease (because the relationship is an inverse relationship, so if m increases, v must decrease).