A20 kg shopping cart moving at a velocity of 0.5 m/s collides with a store wall and stops. the momentum of the shopping cart
a. increases.
b. decreases.
c. remains the same.
d. is conserved.

B. decreases

Explanation:

The momentum of an object is

p = mv

where

m is the mass of the object

v is its velocity

At the beginning, the momentum of the cart is

where

m = 20 kg is the mass of the cart

v = 0.5 m/s is the initial velocity

After colliding with the wall, however, the cart comes to a stop: this means that its final velocity is zero (v=0), so its new momentum is

Therefore, the momentum of the cart has decreased, and the correct option is B.