A meter stick is balanced at the 50cm mark. You tie a 20N weight at the 20cm mark. Where should a 15N weight be placed so the meter stick will again be balanced?

Abeam of electrons with of wavelength of 7.5 x 10-6 m is incident on a pair of narrow rectangular slits separated by 0.75 mm. the resulting interference pattern is projected onto a screen 10.0 m from the slits. what is the separation of the interference maxima in the resulting interference pattern?

Work out sian speed for the first 30 minutes of her journey. give your answer in km/h.

Why should seat belts not be mandatory quick plz