Since astronauts in orbit are apparently weightless, a clever method of measuring their masses is needed to monitor their mass gains or losses to adjust diets. one way to do this is to exert a known force on an astronaut and measure the acceleration produced. suppose a net external force of 49.0 n is exerted and the astronaut's acceleration is measured to be 0.780 m/s2. calculate her mass in kilograms.

Identify the type of synthetic material used in each object

One day, after pulling down your window shade, you notice that sunlight is passing through a pinhole in the shade and making a small patch of light on the far wall. you see that the patch of light seems to be a circular diffraction pattern. it appears that the central maximum is about 1 cm across and you estimate that the distance from the window shade to the wall is about 3 m. what is (a) the average wavelength of sunlight? (b) the diameter of the pinhole?

Glass has a hardness that is in the middle of the hardness scale. what is the hardness of glass?