| DENSITY | The ratio of the mass of a substance to its volume (7) |
| BOYLE | Who stated the law that the pressure of a given mass of gas is inversely proportional to its volume at constant temperature (5) |
| MICROGRAM | One is roughly the mass of a speck of dust |
| AMU | 1/12 the mass of a carbon atom (Ab.) |
| SECANT | In trigonometry, the ratio of the hypotenuse of a right-angled triangle to that of the adjacent side; the reciprocal of the cosine (6) |
| SINE | A trigonometric function that in a right-angled triangle is the ratio of the length of the opposite side to that of the hypotenuse |
| EFFICIENCY | A measure of a mechanical system's effectiveness, usually the ratio of the power delivered by a mechanical system to the power supplied to it (10) |
| MACH | Physicist who established the principles of supersonics and the ratio of the velocity of a body to the speed of sound (4) |
| NEPER | Unit used in physics to express the ratio of two quantities, equal to the natural logarithm of the ratio of the quantities (5) |
| TANGENT | Ratio of the opposite to the adjacent side of a right-angled triangle. (7) |
| COSECANT | In geometry, the ratio of the length of the hypotenuse in a right-angled triangle to that of the opposite side (8) |
| ENERGID | The nucleus of a cell together with the mass of protoplasm around it (7) |
| ARALSEA | Formerly large saltwater lake in Kazakhstan and Uzbekistan that has lost around 90% of its volume since the 1960s (4,3) |
| SERVICE | It could be the mass of the army (7) |
| RATEOFRETURN | The ratio of the annual income from an investment to the original investment, often expressed as a percentage (4,2,6) |
| MPH | The ratio of the distance traveled (in miles) to the time spent traveling (in hours). |
| DETRIMENT | In physics, the ratio of the amplitudes in successive cycles of a damped oscillator (9) |
| PERSPEX | Plastic expropriates the ratio, lost in the difficulty (7) |
| WEIGHED | Determined the mass of (7) |
| ICEBERG | Decorate Austrian composer for the 'Mass of Antarctica'? |
