An astronaut on a distant planet wants to determine its acceleration due to gravity. The astronaut throws the rock straight up with a velocity of + 15 m/s and measures a time of 20.0 seconds before the rock returns to his hand. What is the acceleration (magnitude and direction) due to gravity on this planet?

What sort of waves exhibit the doppler effect?

Rank the six combinations of electric charges on the basis of the electric force acting on q1. define forces pointing to the right as positive and forces pointing to the left as negative. rank positive forces as larger than negative forces. q1,q2,q3 = positive(+) q1 = + q2 = + q3 = - q1 = + q2= - q3= + q1= - q2= + q3= + q1= + q2= - q3= - q1,q2,q3 = negative

How can waves travel through ground?