What's the difference between acceleration and velicity?

I've been learning how to calculate wavelength and I don't get it at all.

Explain why total internal reflection has make communication much faster through the use of fibre optic cables.

Describe what might happen if Earth's magnetic field continues to lose strength.

An object of mass m is lowered at constant velocity at the end of a string of negligible mass. As it is lowered a vertical distance h, its gravitational potential energy changes by ∆Ug = - m g h.

Two masses are joined by a massless string. A 30-N force applied vertically to the upper mass gives the system a constant [Ans : 490 N] [Ans : 1.3 * 10-23 m] [Ans : 19 cm] [Ans : 1.96 ms-2 ] [Ans : 680 m] upward acceleration of 3.2 m / s 2.

Is it possible to have a weak acid or base?

Why does an object accelerate when falling to earth's surface?

2.5 g of helium at an initial temperature of 300 K interacts thermally with 9.0 g of oxygen at an initial temperature of 620 K.

34. A steam engine operates between 300K and 600K, the maximum possible efficiency of this engine is a. 100% b. 75% c. 50% d. 25%

How many moles of phosphorus trichloride are in 200 grams of the molecule? 62.67 mol 27,466.6 mol 1.46 mol 0.69 mol