Marek is trying to push a box of sports equipment across the floor. The arrow on the box is a vector showing the force Marek exerts. 1. Describe all the forces acting on the box.
2.Explain what needs to happen for the box to start moving.

The first law of thermodynamics states that heat added to a system is neither created nor destroyed but is transformed ⇒ as it changes into other forms of energy.

Carbon is allowed to diffuse through a steel plate 15 mm thick. the concentrations of carbon at the two faces are 0.65 and 0.30 kg c/m^3 fe, which are maintained constant. if the preexponential and activation energy are 6.2 x 10-7 m2 /s and 80,000 j/mol, respectively, compute the temperature at which the diffusion flux is 1.43 x 10^-9 kg/m^2 -s.

You throw a ball upward and let it fall to the ground. your friend drops an identical ball straight down to the ground from the same height. is the change in kinetic energy (from just after the ball is released until just before it hits the ground) of your ball greater than, less than, or equal to the change in kinetic energy of your friend's ball?