Use the equation of gravitational force, that is, use F=-G (m1)(m2)/r^2, to find the weight of a crate whose mass is 30 kg. The Earth’s mass is 6x 10^24 kg, and its radius is 6.4x 10^6 m. ( G =-6.67x10^-11)

Mechanical energy is when the amount of kinetic and potential energies added together remains the same. conserved created lost

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

The direction of the current in an alternating current circuit remains constant. is direct. changes repeatedly. changes randomly.