30 terms

# Quiz 8

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A 30-kg child rides on a circus Ferris wheel that takes her around a vertical circular path with a radius of 20 m every 22 s. What is the magnitude of the resultant force on the child at the highest point on this trajectory?
Question options:
1) 49 N
2) 0.29 kN
3) 0.34 kN
4) 0.25 kN
5) 0.76 kN
1) 49 N
A 0.50-kg mass attached to the end of a string swings in a vertical circle (radius = 2.0 m). When the string is horizontal, the speed of the mass is 8.0 m/s. What is the magnitude of the force of the string on the mass at this position?
Question options:
1) 16 N
2) 17 N
3) 21 N
4) 11 N
5) 25 N
1) 16 N
A race car traveling at 100 m/s enters an unbanked turn of 400 m radius. The coefficient of (static) friction between the tires and the track is 1.1. The track has both an inner and an outer wall. Which statement is correct?
Question options:
1) The race car will crash into the outer wall.
2) The race car will crash into the inner wall.
3) The car will stay in the center of the track.
4) The car will stay in the center of the track if the driver speeds up.
5) The car would stay in the center of the track if the radius were reduced to 200 m.
1) The race car will crash into the outer wall.
A 50-kg child riding a Ferris wheel (radius = 10 m) travels in a vertical circle. The wheel completes one revolution every 10 s. What is the magnitude of the force on the child by the seat at the highest point on the circular path?
Question options:
1) 0.29 kN
2) 0.49 kN
3) 0.69 kN
4) 0.20 kN
5) 0.40 kN
1) 0.29 kN
An airplane flies in a horizontal circle of radius 500 m at a speed of 150 m/s. If the radius were changed to 1000 m, but the speed remained the same, by what factor would its centripetal acceleration change?
Question options:
1) 0.25
2) 0.50
3) 1.00
4) 2.00
5) 4.00
2) 0.50
A split highway has a number of lanes for traffic. For traffic going in one direction, the radius for the inside of the curve is half the radius for the outside. One car, car A, travels on the inside while another car of equal mass, car B, travels at equal speed on the outside of the curve. Which statement about resultant forces on the cars is correct?
Question options:
1) The force on A is half the force on B.
2) The force on B is half the force on A.
3) The force on A is four times the force on B.
4) The force on B is four times the force on A.
5) There is no net resultant force on either as long as they stay on the road while turning.
2) The force on B is half the force on A.
A 4.0-kg mass on the end of a string rotates in a circular motion on a horizontal frictionless table. The mass has a constant speed of 2.0 m/s and the radius of the circle is 0.80 m. What is the magnitude of the resultant force acting on the mass?
Question options:
1) 39 N
2) 20 N
3) 44 N
4) 0 N
5) 30 N
2) 20 N
A stunt pilot weighing 0.70 kN performs a vertical circular dive of radius 0.80 km. At the bottom of the dive, the pilot has a speed of 0.20 km/s which at that instant is not changing. What force does the plane exert on the pilot?
Question options:
1) 3.6 kN up
2) 4.3 kN up
3) 2.9 kN down
4) 2.9 kN up
5) 5.8 kN down
2) 4.3 kN up
A car travels around an unbanked highway curve (radius 0.15 km) at a constant speed of 25 m/s. What is the magnitude of the resultant force acting on the driver, who weighs 0.80 kN?
Question options:
1) 0.87 kN
2) 0.34 kN
3) 0.80 kN
4) 0.00 kN
5) 0.67 kN
2) 0.34 kN
A 0.50 kg mass attached to the end of a string swings in a vertical circle (radius = 2.0 m). When the mass is at the highest point of the circle the speed of the mass is 8.0 m/s. What is the magnitude of the force of the string on the mass at this position?
Question options:
1) 21 N
2) 11 N
3) 16 N
4) 26 N
5) 36 N
2) 11 N
An airplane moves 140 m/s as it travels around a vertical circular loop which has a 1.0-km radius. What is the magnitude of the resultant force on the 70-kg pilot of this plane at the bottom of this loop?
Question options:
1) 2.1 kN
2) 1.4 kN
3) 0.69 kN
4) 1.5 kN
5) 1.3 kN
2) 1.4 kN
A race car travels 40 m/s around a banked (45° with the horizontal) circular (radius = 0.20 km) track. What is the magnitude of the resultant force on the 80-kg driver of this car?
Question options:
1) 0.68 kN
2) 0.64 kN
3) 0.72 kN
4) 0.76 kN
5) 0.52 kN
2) 0.64 kN
For a plane to be able to fly clockwise in a horizontal circle as seen from above, in addition to exerting a force downwards on the air
Question options:
1) it must be increasing its speed.
2) it must exert a force on the air that is directed to the plane's left side.
3) it must exert a force on the air that is directed to the plane's right side.
4) it does not need to exert a force: it must only move the wing flaps out.
5) it only needs to deflect the air without exerting any additional force on the air.
2) it must exert a force on the air that is directed to the plane's left side.
A 0.50-kg mass attached to the end of a string swings in a vertical circle (radius = 2.0 m). When the mass is at the lowest point on the circle, the speed of the mass is 12 m/s. What is the magnitude of the force of the string on the mass at this position?
Question options:
1) 31 N
2) 36 N
3) 41 N
4) 46 N
5) 23 N
3) 41 N
A boy on board a cruise ship drops a 30.0 gm marble into the ocean. If the resistive force proportionality constant is 0.500 kg/s, what is the terminal speed of the marble in m/s?
Question options:
1) 0.147
2) 0.294
3) 0.588
4) 1.18
5) 2.35
3) 0.588
Two small cylindrical plastic containers with flat bottoms are placed on a turntable that has a smooth flat surface. Canister A is empty; canister B contains lead shot. Each canister is the same distance r from the center. The coefficient of static friction between the canisters and the turntable is ms. When the speed of the turntable is gradually increased,
Question options:
1) only the lighter container slides outward off the turntable; the heavier one stays on.
2) only the heavier container slides outward off the turntable; the lighter one stays on.
3) both containers slide off the turntable at the same turntable speed.
4) the lighter container slides inward.
5) the heavier container slides inward.
3) both containers slide off the turntable at the same turntable speed.
A hornet circles around a pop can at constant speed once per second in a path with a 12-cm diameter. We can conclude that the hornet's wings must push on the air with force components that are
Question options:
1) straight down.
2) down and inwards.
3) down and outwards.
4) down and backwards.
5) down, inwards and backwards.
3) down and outwards
When a car goes around a circular curve on a level road,
Question options:
1) no frictional force is needed because the car simply follows the road.
2) the frictional force of the road on the car increases when the car's speed decreases.
3) the frictional force of the road on the car increases when the car's speed increases.
4) the frictional force of the road on the car increases when the car moves to the outside of the curve.
5) there is no net frictional force because the road and the car exert equal and opposite forces on each other.
3) the frictional force of the road on the car increases when the car's speed increases.
An iceboat is traveling in a circle on the ice. Halfway around the circle the sail and the steering mechanism fall off the boat. Which statement is correct?
Question options:
1) The boat will continue traveling in the circle because there is no friction.
2) The boat will continue to travel in the circle because its velocity exerts a force on it.
3) The boat will move off on a line tangent to the circle because there is no force on it.
4) The boat will move off tangent to the circle because there is a force on it perpendicular to the boat directed to the outside of the circle.
5) The boat will move off to the outside perpendicular to the tangent line since a force directed to the outside of the circle always acts on the boat.
3) The boat will move off on a line tangent to the circle because there is no force on it.
A 0.20-kg object attached to the end of a string swings in a vertical circle (radius = 80 cm). At the top of the circle the speed of the object is 4.5 m/s. What is the magnitude of the tension in the string at this position?
Question options:
1) 7.0 N
2) 2.0 N
3) 3.1 N
4) 5.1 N
5) 6.6 N
3) 3.1 N
A car enters a level, unbanked semi-circular hairpin turn of 100 m radius at a speed of 28 m/s. The coefficient of friction between the tires and the road is m = 0.800. If the car maintains a constant speed of 28 m/s, it will
Question options:
1) attempt to dig into the road surface.
2) tend to veer toward the center of the semicircle.
3) arrive safely at the end of the semicircle.
4) tend to veer toward the outside of the circle.
5) veer toward the center for the first quarter-circle, then veer toward the outside for the second quarter-circle.
3) arrive safely at the end of the semicircle.
A car travels along the perimeter of a vertical circle (radius = 0.25 km) at a constant speed of 30 m/s. What is the magnitude of the resultant force on the 60-kg driver of the car at the lowest point on this circular path?
Question options:
1) 0.37 kN
2) 0.80 kN
3) 0.22 kN
4) 0.59 kN
5) 0.45 kN
3) 0.22 kN
A 0.40-kg mass attached to the end of a string swings in a vertical circle having a radius of 1.8 m. At an instant when the string makes an angle of 40 degrees below the horizontal, the speed of the mass is 5.0 m/s. What is the magnitude of the tension in the string at this instant?
Question options:
1) 9.5 N
2) 3.0 N
3) 8.1 N
4) 5.6 N
5) 4.7 N
3) 8.1 N
A highway curve has a radius of 0.14 km and is unbanked. A car weighing 12 kN goes around the curve at a speed of 24 m/s without slipping. What is the magnitude of the horizontal force of the road on the car?
Question options:
1) 12 kN
2) 17 kN
3) 13 kN
4) 5.0 kN
5) 49 kN
4) 5.0 kN
A car enters a level, unbanked semi-circular hairpin turn of 300 m radius at a speed of 40 m/s. The coefficient of friction between the tires and the road is m = 0.25. If the car maintains a constant speed of 40 m/s, it will
Question options:
1) attempt to dig into the road surface.
2) tend to veer toward the center of the semicircle.
3) arrive safely at the end of the semicircle.
4) tend to veer toward the outside of the circle.
5) veer toward the center for the first quarter-circle, then veer toward the outside for the second quarter-circle.
4) tend to veer toward the outside of the circle.
In a recent mystery, the hero saves himself by spreading out a windshield tarpaulin to reduce his terminal velocity. A skydiver of 75 kg mass has a terminal velocity of 60 m/s. If the hero has the same 75 kg mass, the same density as the sky diver, and a drag coefficient twice as large with the tarp, by what factor is his effective area greater than the 0.70 m2 area of the skydiver?
Question options:
1) 4
2) 8
3) 16
4) 32
5) 64
4) 32
An airplane flies in a horizontal circle of radius 500 m at a speed of 150 m/s. If the plane were to fly in the same 1000 m circle at a speed of 300 m/s, by what factor would its centripetal acceleration change?
Question options:
1) 0.25
2) 0.50
3) 1.00
4) 2.00
5) 4.00
4) 2.00
An airplane travels 80 m/s as it makes a horizontal circular turn which has a 0.80-km radius. What is the magnitude of the resultant force on the 75-kg pilot of this airplane?
Question options:
1) 0.69 kN
2) 0.63 kN
3) 0.66 kN
4) 0.60 kN
5) 0.57 kN
4) 0.60 kN
A student is sitting on the right side of a school bus when it makes a right turn. We know that the force of gravity acts downwards and a normal force from the seat acts upwards. If the student stays in place when the bus turns, we also know that there must be
Question options:
1) no other force on the student.
2) a force parallel to the seat directed forward on the student.
3) a force parallel to the seat directed to the left on the student.
4) a force parallel to the seat directed to the right on the student.
5) a force parallel to the seat in a direction between forward and left on the student.
4) a force parallel to the seat directed to the right on the student.
An amusement ride consists of a car moving in a vertical circle on the end of a rigid boom. The radius of the circle is 10 m. The combined weight of the car and riders is 5.0 kN. At the top of the circle the car has a speed of 5.0 m/s which is not changing at that instant. What is the force of the boom on the car at the top of the circle?
Question options:
1) 3.7 kN (Down)
2) 1.3 kN (Down)
3) 6.3 kN (Up)
4) 3.7 kN (Up)
5) 5.2 kN (Down)
4) 3.7 kN (Up)