The radius of a calcium atom is approximately 0. 23 nm.

Acheetah ran 75 meters at a speed of 25 meters per second. how long was the cheetah running? 3 seconds 5 seconds 30 seconds 50 seconds

How do refracting telescopes magnify a far away image? a. by directing light beams to meet at a focal point b. by absorbing light beams’ wavelengths c. by forcing light beams to change direction d. by measuring light beams’ velocity

Ateacher attaches a ball to a meter long string and whirls it around in a horizontal circle at constant speed. the teacher explains that the string is what makes the ball go in a circle. why is the string necessary? a) the string is needed to apply a torque to the ball. b) the string is needed to push on the ball to get it up to speed. c) circle motion requires an inertia which is provided by the string. d) circle motion requires a force to give it a centripetal acceleratio