Why is an si measurement system so important in the science comunity?

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

Ahorizontal wire is tied to supports at each end and vibrates in its second-overtone standing wave. the tension in the wire is 5.00 n, and the node-to-node distance in the standing wave is 6.28 cm. (a) what is the length of the wire? (b) a point at an anti- node of the standing wave on the wire travels from its maximum upward displacement to its maximum downward displacement in 8.40 ms. what is the wire's mass?

Adding more pulleys to a system of pulleys needed to lift an object. a. increases the force b. decreases the force c. increases the amount of work d. decreases the amount of work