Achild pulls a 15 kg sled containing a 5.0 kg dog along a straight path on a horizontal surface. he exerts a force of 55 n on the sled at an angle of 20 degrees above the horizontal. the coefficient of friction between the sled and the surface is 0.22.calculate the word done by the child's pulling force as the system moves a distance of 7.0 m.

What structural formula represents 4 electrons shared between two atoms?

Petroleum contains energy. a. light b. kinetic c. chemical d. mechanical

Awelder using a tank of volume 7.50×10^-2 m^3 fills it with oxygen (with a molar mass of 32.0 g/mol ) at a gauge pressure of 3.30×10^5 pa and temperature of 37.1 ∘c. the tank has a small leak, and in time some of the oxygen leaks out. on a day when the temperature is 23.1 ∘c, the gauge pressure of the oxygen in the tank is 2.00×10^5 pa . a) find the initial mass of oxygen. b) find the mass of oxygen that has leaked out.