Vận tốc của chất điểm dao động điều hoà có độ lớn cực đại khi ?

where is the photo and the answer choices?

force tends to be low and long diustance masses are high

see the picture for the vector

the magnitude of the vector by pythagorean theorem

r = √( (-10)^2 + (3)^2 ) = √109

magnitude = √109 units

the direction angle between vector and x-axis is

tan^(-1)(3/10) = 16.699

so the direction is approximately 16.7 degrees north of west