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Two horizontal forces, F, and F,, are acting on a box, but only F, is shown in the drawing. F, can point either to the right or to the left. The box moves only along the x axis. There is no friction between the box and the surface. Suppose that F, = +4.6 N and the mass of the box is 4.2 kg. Find the magnitude and direction of F, when the acceleration of the box is (a) +6.3 m/s2, (b) -6.3 m/s?, and (c) 0 m /52. F -+X (a) (b) F2 = V V (c) F, = VIn the amusement park ride known as Magic Mountain Superman, powerful magnets accelerate a car and its riders from rest to 34.2 m/s in a time of 6.56 s. The mass of the car and riders is 7.36 x 10 kg. Find the average net force exerted on the car and riders by the magnets. Number i UnitsThe space probe Deep Space 1 was launched on October 24, 1998. Its mass was 474 kg. The goal of the mission was to test a new kind of engine called an ion propulsion drive. This engine generated only a weak thrust, but it could do so over long periods of time with the consumption of only small amounts of fuel. The mission was spectacularly successful. At a thrust of 56 mN how many days were required for the probe to attain a velocity of 765 m/s (1710 mi/h), assuming that the probe started from rest and that the mass remained nearly constant? t = Number i UnitsTwo 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 85 kg, and the mass of the woman is 54 kg. The woman pushes on the man with a force of 65 N due east. Determine the acceleration [magnitude and direction]I of la} the man and [b] the woman. la}aman= n v v tb)amm= n v v A 9.0 kg rock and a 3.0 X 10'4kg pebble are held near the surface of the earth. [3} Determine the magnitude of the gravitational force exerted on each by the earth. (bl Calculate the magnitude of the acceleration of each object when released. (a) Frock = n v Fpehble = n V {b} amck = n v apebble = n V The sun is more massive than the moon, but the sun is fartherfrom the earth. Which one exerts a greater gravitational force on a person standing on the earth? Give your answer by determining the ratio FsuanmDn of the magnitudes of the gravitational forces. Use the data on the inside of the front cover. Number Units V A woman stands on a scale in a moving elevator. Her mass is 68.0 kg, and the combined mass of the elevator and scale is an additional 732 kg. Starting from rest, the elevator accelerates upward. During the acceleration, the hoisting cable applies a force of 9510 N. What does the scale read (in N) during the acceleration? Number i UnitsConsult Multiple-Concept Example 9 to explore a model for solving this problem. A person pushes on a 55-kg refrigerator with a horizontal force of -270 N; the minus sign indicates that the force points in the -x direction. The coefficient of static friction is 0.59. (a) If the refrigerator does not move, what are the magnitude and direction of the static frictional force that the floor exerts on the refrigerator? (b) What is the magnitude of the largest pushing force that can be applied to the refrigerator before it just begins to move? Assumeg = 9.8 m/s2. (a) Static frictional force (b) Magnitude of largest force = vDu ring a storm, a tree limb breaks off and comes to rest across a barbed wire fence at a point that is not in the middle between two fence posts. The limb exerts a downward force of 252 N on the wire. The left section of the wire makes an angle of 12.3\" relative to the horizontal and sustains a tension of 436 N. Find the {a} magnitude and {b} direction (as an angle relative to horizontal) of the tension that the right section of the wire sustains. (a) Number n Units V {b} Number Units V Review Conceptual Example 16 as background for this problem. The water skier there has a mass of 80.0 kg. Find the magnitude of the net force acting on the skier when (a) she is accelerated from rest to a speed of 10.0 m/s in 6.90 s and (b) she lets go of the tow rope and glides to a halt in 22.0 s. (a) Number i Units (b) Number i Units v