A block of mass m=4.50 kg is released from rest from point A and slides on the frictionless track shown in the figure below assume ha = 6.00 m. Determine the block’s speed at points B and C

A) point B _ m/s
point C _ m/s

B) determine the net work done by the gravitational force on the block as it moves to point A to point C

B) _ J

Arunner is training for an upcoming marathon by running around a 100-m-diameter circular track at constant speed. let a coordinate system have its origin at the center of the circle with the x-axis pointing east and the y-axis north. the runner starts at (x, y) = (50 m, 0 m) and runs 2.5 times around the track in a clockwise direction.

Asheet of steel 1.5 mm thick has nitrogen atmospheres on both sides at 1200oc and is permitted to achieve a steady-state diffusion condition. the diffusion coefficient for nitrogen in steel at this temperature is 6 x 10- 11 m2 /s, and the diffusion flux is found to be 1.2 x 10-7 kg/m2 -s. also, it is known that the concentration of nitrogen in the steel at the high-pressure surface is 4 kg/m3 . how far into the sheet from this high-pressure side will the concentration be 2.0 kg/m3 ? assume a linear concentration profile.

What is the orbital period of a spacecraft in a low orbit near the surface of mars? the radius of mars is 3.4×106m.