Escape room questions, please help me breakout...

Curious carl calculated the density of a cube to be 4.50 g/cm3. what is the density of the cube in g/l?

Which explanation describes the forces involved for a person to walk down the sidewalk? a. the person's feet push backward on the sidewalk; the sidewalk pushes backward on the person. b. the person's feet push forward on the sidewalk; the sidewalk does not push on the person. c. the person's feet push backward on the sidewalk; the sidewalk pushes forward on the person. d. the person's feet push forward on the sidewalk; the sidewalk pushes forward on the person.

It can take some of those large , industrial vehicles up to feet to stop when traveling only 60 mph, and therefore , you shoukd be mindful to not be jn the traffic right in front of them a. 100 feet b. 200 feet c. 335 feet d. 425 feet