Constants are necessary in a controlled experiment because without constants you would not know which variable affected the?

Which of the following is considered to be a vector?               a.  temperature    b.  velocity    c.  time    d.  mass

Apulley system is used to lift a 2,000 newton engine up a distance of 3 meters. the operator must apply a force of 250 newtons to the chain of the pulley system to lift the motor. to lift the engine 3 meters, the operator must pull a total of 30 meters of chain through the pulley system. what is the value of di?

Which sound characteristic is not affected by the relative motion of an object