Question

ECE Review Worksheet 1 AP Physics Mr. Marrash 1. A space traveler weighs 980 N on Earth. What will the traveler weight on another planet whose radius is 3 times that of the Earth and whose mass is also 9 times that of the Earth. Do not use any numerical values of the universal gravitational constant G, the mass of Earth, or the radius of Earth to get your answer. 2. Two skaters, a man and a woman, are standing on ice. Neglect any friction between the skate blades and the ice. The mass of the man is 100 kg, and the mass of the woman is 50 kg. The woman pushes on the man with a force of 50 N in the +x direction at t-0 and x-0. Determine the velocity (magnitude and direction) of the woman at t- 5 s. 3. The punter on a football team tries to kick a football so that it stays in the air for a long "hang time". If the ball is kicked with an initial velocity of 98 m/s at an angle of 30° above the ground, what is the "hang time"? Ignore all air resistance. 4. A boat is traveling at 4.0 m/s as it passes the starting line of a race. If the boat accelerates at 1.0 m/s for 6.0 seconds, what is the average velocity of the boat for the 6.0 seconds? 5. In October 2012, Felix Baumgartner set a world record by skydiving from 120,000 ft. It is reported that he broke the sound barrier during his fall. What is the minimum distance required for him to reach this speed during free fall? Assume that the gravitational acceleration is constant at g 9.8 m/s' over this change in altitude. The speed of sound is 340 m/s. 6. A 5.0 kg mass is moving in a circular path of radius 2.5 m with a constant angular velocity of 6.0 rad/sec. What is the centripetal force on the mass in Newtons? 7. A small ball of mass m -2.2 kg is suspended by a massless string of length L-2.0 m and set in a uniform circular motion. The cord makes an angle of 8- 30° with respect to the vertical. a) What is the value of the tension in the string in Newtons? Page 1 of 2

Answer 1

Acceleration due to gravity is g = squareroot gm/r g earth = squareroot gm_e/r_e weight = mg weight on earth w_e = m rho e = 980 of weight on another planes w' = mg' w'/w = mg'/mg w' = wg'/g = w squareroot gm'/r' rightarrow r_e/gm_e w' = w squareroot 9 u_e/3 r_e r_e/u_e w' = w squareroot 3 = 980 squareroot 3 = 1694.41 n force applied by women on man must be equal to force applied by man on women, accordingly to newton their law f = ma a = f/m = 50/50 = 1 m/s^2 v = u + at = 0 + 1 times 5 = 5 m/s t = 2 u sin theta /g = 2 times 98 times sin 30 degree /9,8 = 10 s s = u + 1/a at^2