Why do slippery fluids such as oil reduce sliding friction

Aforce of 8,480 n is applied to a cart to accelerate it at a rate of 26.5 m/s2. what is the mass of the cart?

Which is a substance that can be separated by physical means and is not the same throughout

Estimate the kinetic energy of mars with respect to the sun as the sum of two terms, that due to its daily rotation about its axis, and that due to its yearly revolution about the sun. (assume mars is a uniform sphere with mass = 6.4×10 to the power of 23 kg, radius = 3.4×10 to the power of 6 m, rotation period = 24.7 hours, orbital period = 686 days and is 2.3×10 to the power of 8 km from the sun.)