A 15.0 m uniform ladder weighing 500 n rests against a frictionless wall. the stair forms an angle of 60.0 ° with the horizontal. (a) find the horizontal and vertical forces exerted by the ground on the base of the ladder when an 800 n firefighter is 4.00 m from the bottom. (b) if the ladder is about to slip when the firefighter is 9.00 m above, what is the coefficient of static friction between the ladder and the ground?

An object thrown vertically upward from the surface of a celestial body at a velocity of 36 m/s reaches a height of sequalsminus0.9tsquaredplus36t meters in t seconds. a. determine the velocity v of the object after t seconds. b. when does the object reach its highest point? c. what is the height of the object at the highest point? d. when does the object strike the ground? e. with what velocity does the object strike the ground? f. on what intervals is the speed increasing?

Which statement is true? a. kepler's laws apply only to the motion of earth. b. kepler's laws can be used to predict eclipses. c. kepler's laws are true for a central force that is directly proportional to distance. d. kepler's laws can be deduced from newton's laws of motion and gravity.

Which compound is held together by the electrostatic force between two ions? a. co2 b. cci4 c. h2s d. mgf2