OC userin Physics·27 Dec 20178) [4 pts] A person is riding on a Ferris wheel. In one complete turn, is the work done on the person by the gravitational force positive, negative, or zero? Explain briefly your answer.
OC userin Physics·26 Dec 20171.39 .. (a) Write each vector in Fig. E1.39 in terms of the unit vectors î and ſ. (b) Use unit vec- tors to express vector C, where C = 3.00 A – 4.00 B. (c) Find the magnitude and direction of C.
OC userin Physics·23 Dec 20172.12 . Figure E2.12 shows the velocity of a solar-powered car as a function of time. The driver accelerates from a stop sign, cruises for 20 s at a constant speed of 60 km/h, and then brakes to come to a stop 40 s after leaving the stop sign. (a) Compute the average acceleration during these time intervals: (i) = 0 to 1 = 10 s; (ii) 1 = 30 s to t = 40 s; (iii) = 10 s to 1 = 30 s: (iv) t = 0 tot = 40 s. (b) What is the instantaneous acceleration at 20 s and att = 35 s? Figure E2.12 v (km/h) 8 o 5 10 15 20 25 30 35 40
OC userin Physics·24 Dec 2017Q1.16 (a) Does it make sense to say that a vector is negative? Why? (b) Does it make sense to say that one vector is the negative of another? Why? Does your answer here contradict what you said in part (a)?
OC userin Physics·23 Dec 20175.1. Two 25.0-N weights are suspended at opposite ends of a rope that passes over a light, frictionless pulley. The pulley is attached to a chain from the ceiling, (a) What is the tension in the rope? (b) What is the tension in the chain?
OC userin Physics·21 Dec 201777. Bromine has two naturally occurring isotopes (Br-79 and Br-81) and has an atomic mass of 79.904 amu. The mass of Br-81 is 80.9163 amu, and its natural abundance is 49.31%. Calculate the mass and natural abundance of Br-79.
OC userin Physics·22 Dec 201711.1. A 0.120-kg, 50.0-cm-long uniform bar has a small 0.055-kg mass glued to its left end and a small 0.110-kg mass glued to the other end. The two small masses can each be treated as point masses. You want to balance this system horizontally on a fulcrum placed just under its center of gravity. How far from the left end should the fulcrum be placed?
OC userin Physics·20 Dec 201769. Which pair of elements do you expect to be most similar? Why? a. Nand Ni b. Mo and Sn c. Na and Mg d. Cl and F e. Si and P
OC userin Physics·21 Dec 20172.28 . Entering the Freeway. A car sits on an entrance ramp to a freeway, waiting for a break in the traffic. Then the driver ac- celerates with constant acceleration along the ramp and onto the freeway. The car starts from rest, moves in a straight line, and has a speed of 20 m/s (45 mi/h) when it reaches the end of the 120-m- long ramp. (a) What is the acceleration of the car? (b) How much time does it take the car to travel the length of the ramp? (c) The traffic on the freeway is moving at a constant speed of 20 m/s. What distance does the traffic travel while the car is moving the length of the ramp?
OC userin Physics·20 Dec 20175.19 .. CP A 750.0-kg boulder is raised from a quarry 125 m deep by a long uniform chain having a mass of 575 kg. This chain is of uniform strength, but at any point it can support a maximum tension no greater than 2.50 times its weight without breaking. (a) What is the maximum acceleration the boulder can have and still get out of the quarry, and (b) how long does it take to be lifted out at maximum acceleration if it started from rest?
OC userin Physics·19 Dec 20175.63 . In a repair shop a truck engine that has mass 409 kg is held in place by four light cables (Fig. P5.63). Cable A is horizon- tal, cables B and D are vertical, and cable C makes an angle of 37.1" with a vertical wall. If the tension in cable A is 722 N, what are the tensions in cables B and C? Figure P5.63
OC userin Physics·19 Dec 201714.39. A thrill-seeking cat with mass 4.00 kg is attached by a harness to an ideal spring of negligible mass and oscillates vertically in SHM. The amplitude is 0.050 m, and at the highest point of the motion the spring has its natural unstretched length. Calculate the elastic potential energy of the spring (take it to be zero for the unstretched spring), the kinetic energy of the cat, the gravitational potential energy of the system relative to the lowest point of the motion, and the sum of these three energies when the cat is (a) at its highest point; (b) at its lowest point; (c) at its equilibrium position.
OC userin Physics·18 Dec 201772. Magnesium has three naturally occurring isotopes with the fol- lowing masses and natural abundances: Isotope Mg-24 Mg-25 Mg-26 Mass (amu) 23.9850 24.9858 25.9826 Abundance (%) 78.99 10.00 11.01 Sketch the mass spectrum of magnesium.
OC userin Physics·19 Dec 201725.3.A 5.00-A current runs through a 12-gauge copper wire (diameter 2.05 mm) and through a light bulb. Copper has 8.5 X 10 free electrons per cubic meter. (a) How many electrons pass through the light bulb each second? (b) What is the current density in the wire? (c) At what speed does a typical electron pass by any given point in the wire? (d) If you were to use wire of twice the diameter, which of the above answers would change? Would they increase or decrease?