How does mass effect potential and kinetic energy on a roller coaster?

Part a constants huck finn walks at a speed of 0.60 m/s across his raft (that is, he walks perpendicular to the raft's motion what is huck's velocity (speed and direction) relative to the river bank? express your answer to three significant figures and include the appropriate units. relative to the shore)

A51 kg woman skis down a hill and her kinetic energy is 9.96e4 j. what is her speed?

Hi , i am new here can anyone me out with this question why is space black after having so many shining objects like sun , moon , stars