Question

Kara and John are pushing their grocery carts along a flat surface in a store. Kara's cart is empty, and John's cart is full.



Kara and John each push their cart with the same force. Why does Kara's cart speed up more than John's cart when they push with the same force?
A.
because her cart has more friction acting on it
B.
because her cart needs no force to push it
C.
because no gravity is acting on her cart
D.
because her cart has less mass

Answer 1

D. because her cart has less mass

According to Newton's second law, a = F/m. With the same applied force, the cart with smaller mass (Kara's empty cart) undergoes a larger acceleration, so it speeds up more.