An electron is projected with an initial speed vi = 3.35 × 10^5 m/s directly toward a very distant proton that is at rest. because the proton mass is large relative to the electron mass, assume that the proton remains at rest. by calculating the work done on the electron by the electrostatic force, determine the distance between the two particles when the electron instantaneously has speed 2vi.

4. if you were an astronaut on the moon, what would you experience? what would you see from your perspective?

Emmy kicks a soccer ball up at an angle of 45° over a level field. she watches the ball's trajectory and notices that it lands, two seconds after being kicked, about 20 m away to the north. assume that air resistance is negligible, and plot the horizontal and vertical components of the ball's velocity as a function of time. consider only the time that the ball is in the air, after being kicked but before landing. take "north" and "up" as the positive ‑ and ‑directions, respectively, and use ≈10 m/s2 for the downward acceleration due to gravity.

Water is siphoned from a large tank and discharges into the atmosphere through a 50-mm diameter tube. the end of the tube is b = 2.6 m below the tank bottom which is a = 6.7 m deep, and viscous effects are negligible. determine the maximum height h over which the water can be siphoned without cavitation occurring. atmospheric pressure is 101.4 kpa, and the water vapor pressure is 1.79 kpa (absolute). report your answer in meters to two decimal places.