**Answer: Yes and no.**

**Explanation: Mass is the amount of matter in an object, whereas weight is the force exerted on an object by gravity. Objects on the surface of the earth have weight, although sometimes the weight is difficult to measure.**

**Answer:**

One second is defined by taking the fixed numerical value of the caesium frequency ∆ν, the unperturbed ground-state hyperfine transition frequency of the caesium 133 atom, to be 9 192 631 770 (9.192631770 x 10⁹ ) cycles of the radiation, when expressed in the unit Hz, which is equal to s−¹.

One second is equal to 1/86,400 of a mean solar day.

**Answer:**

**Explanation:**

We just have to calculate what **angular displacement** a ball with an average **angular velocity** of 290 rev/min experiments **in** 0.64s. By definition, angular velocity is the angular displacement divided by the time elapsed:

Since and , we can covert:

Where the terms between parenthesis are equal to 1, so they just change the units. Then for our values we have: