5. A truck is moving on the road on a circular path with a radius of curvature of 60 m. The road has a frictional coefficient 0.70. Find the speed limit so the truck will not skid sideways. Scre

A car is driving around a flat, circularly curved road with a radius of 5.00 102 m. The mass of the car is 1500 kg, and the coefficient of static friction between its tires and the road is 0.30. a. Using the work of Example 6.7 (pages 202203), what is the maximum speed the car can have without slipping? b. What is the magnitude of the centripetal force on the car if it were to travel at the maximum speed around the track?

CASE STUDY In the train collision case study (Chapter 5, page 119), we ignored the drag force on the trains. Estimate the drag on the trains and compare it to the kinetic friction on them. Is it okay to ignore drag? Explain.

Lisa measured the coefficient of static friction between two pairs of running shoes and the track in Example 6.1 (page 159). If she wants to have an advantage in a race, which shoes should she wear, the ones with a high coefficient or the ones with the low coefficient of static friction? Explain.

The drag coefficient C in FD=12CAv2 (Eq. 6.5) depends primarily on the shape of the object. You already have developed an intuition about what shapes correspond to a low C by observing the shapes of aerodynamic cars, boats, and even bullets. Which object, a sphere or a cube, would have a larger drag coefficient, assuming they are nearly the same size? Explain your reasoning. What aspect of an object most determines its drag coefficient?

To maintain a constant speed, the force provided by a car’s engine must equal the drag force plus the force of friction of the road (the rolling resistance). (a) What are the drag forces at 70 km/h and 100 km/h for a Toyota Camry? (Drag area is 0.70m2 ) (b) What is the drag force at 70 km/h and 100 km/h for a Hummer H2? (Drag area is 2.44m2 ) Assume all values are accurate to three significant digits.

The maximum lift force on a bat is proportional to the square of its flying speed v. For the hoary bat (Lasiurus cinereus), the magnitude of the lift force is given by Fl (0.018 N s2/m2) v2 The bat can fly in a horizontal circle by banking its wings at an angle , as shown in Figure P7.72. In this situation, the magnitude of the vertical component of the lift force must equal the bats weight. The horizontal component of the Figure P7.72. force provides the centripetal acceleration. (a) What is the minimum speed that the bat can have if its mass is 0.031 kg? (b) If the maximum speed of the bat is 10 m/s, what is the maximum banking angle that allows the bat to stay in a horizontal plane? (c) What is the radius of the circle of its flight when the bat flies at its maximum speed? (d) Can the bat turn with a smaller radius by flying more slowly?

In a race like the Indianapolis 500, a driver circles the track counterclockwise and feels his head pulled toward one shoulder. To relieve his neck muscles from having to hold his head erect, the driver fastens a strap to one wall of the car and the other to his helmet. The length of the strap is adjusted to keep his head vertical. (a) Which shoulder does his head tend to lean toward? (b) What force or forces produce the centripetal acceleration when there is no strap? (c) What force or forces do so when there is a strap?

The mass of a roller-coaster car, including its passengers, is 500 kg. Its speed at the bottom of the track in Figure P6.16 is 19 m/s. The radius of this section of the track is r1 = 25 m. Find the force that a seat in the roller-coaster car exerts on a 50-kg passenger at the lowest point.

A filled treasure chest of mass m with a long rope tied around its center lies in the middle of a room. Dirk wishes to drag the chest, but there is friction between the chest and the floor with a coefficient of static friction s. If the angle between the rope and the floor is , what is the magnitude of the tension required to just get the chest moving? Express your answer in terms of m, s, , and g.