A contestant in a winter sporting event pushes a 45.0-kg block of ice across a frozen lake as shown below. The coefficient of friction of ice is 0.1. (a) Calculate the minimum force
F he must exert to get the block moving. (b) What is its acceleration once it starts to
move, if that force is maintained?

One day, after pulling down your window shade, you notice that sunlight is passing through a pinhole in the shade and making a small patch of light on the far wall. you see that the patch of light seems to be a circular diffraction pattern. it appears that the central maximum is about 1 cm across and you estimate that the distance from the window shade to the wall is about 3 m. what is (a) the average wavelength of sunlight? (b) the diameter of the pinhole?

Explain how the energy of rubber ball is tranforned as it roll down a ramp. give evidence that the energy of the og the ball remains the same at all points on the ramp

(a) if the pressure in gas is doubled while its volume is held constant, by what factor do (i) vrms and (ii) change? (b) is it possible to boil water at room temperature (20oc) without heating it? explain.