A ball dropped from rest falls freely until it hits the ground with a speed of 18 meters per second. How long did it take for the ball to reach the ground?

Determine the critical height h of the water level that causes the concrete gravity dam to be on the verge of tipping over due to water pressure. the density of concrete is ρc = 2.40 mg/m3. suppose that hd = 38 m. hint: work the problem using a 1-m width of the dam.

Can you use radiation to generate electricity

What is the electric force acting between two charges of -0.0045 c and -0.0025 c that are 0.0060 m apart? use fe=kq1q2/r^2 and k = 9.00 x 10^9 n*m^2/c^2 a. 1.7 x 10^7 n b. -1.7 x 10^7 n c. -2.8 x 10^9 n d. 2.8 x 10^9 n