If Cindy and Chris both push on a box with a force of 15 N, in the same direction, how much force is applied to the box?

Your 249 ml cup of coffee is too hot to drink when served at 82 degree celsius. what is the mass of an ice cube taken from a -21 degree celsius freezer, that will cool your coffee to a pleasant 54 degree celsius. specific heat of the water is 4190 j/kg c, specific heat of ice is 2090 j/kg c, heat of fusion of ice is 3.33 x 10^5 j/kg

What happens to the light rays when they hit the specimen?

Imagine that someone pushes one marble toward a motionless marble. would there still be action-reaction forces involved in the collision? how might the marbles’ motions be changed? ?