Section 4.3 Newton's Second Law of Motion 1. An airplane has a mass of 3.] X 10" kg and takes off under the inu- ence of a constant net force of 3.7 X 104 N. What is the net force that acts on the plane's 78-kg pilot? 2. mmh A boat has a mass of 6800 kg. lts engines generate a drive force of 4100 N due west. while the wind exerts a force of 800 N due east and the water exerts a resistive force of 1200 N due east. What are the mag- nitude and direction of the boat's acceleration? 3. Two horizontal forces, is, and i2. are acting on a box. but only if, 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 i, = +90 N and the mass of the box is 3.0 kg. Find the magnitude and direction of F2 when the acceleration of the box is (a) +5.0 mlsz. (b) -5.0 m/sz. and (c) 0 m/sz. Section 4.7 The Gravitational Force 20. Go A 5.0-kg rock and a 3.0 X 10-4-kg pebble are held near the sur- face of the earth. (a) Determine the magnitude of the gravitational force exerted on each by the earth. (b) Calculate the magnitude of the acceler- ation of each object when released.2. Go The following table lists data for the speed and radius of three examples of uniform circular motion. Find the magnitude of the centripetal acceleration for each example.5. ssm How long does it take a plane, traveling at a constant speed of 110 m/s, to fly once around a circle whose radius is 2850 m?. ssm Computer-controlled display screens provide drivers in the Indianapolis 500 with a variety of information about how their cars are performing. For instance, as a car is going through a turn, a speed of 221 mi/h (98.8 m/s) and centripetal acceleration of 3.00 g (three times the acceleration due to gravity) are displayed. Determine the radius of the turn (in meters).16. A speed skater goes around a turn that has a radius of 31 m. The skater has a speed of 14 m/s and experiences a centripetal force of 460 N. What is the mass of the skater?52. mmh A child is twirling a 0.0120-kg plastic ball on a string in a hor- izontal circle whose radius is 0.100 m. The ball travels once around the circle in 0.500 s. (a) Determine the centripetal force acting on the ball. (b) If the speed is doubled, does the centripetal force double? If not, by what factor does the centripetal force increase