QuizRP: Physics

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

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.

Answer: 3

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?

1) 7.0 N
2) 2.0 N
3) 3.1 N
4) 5.1 N
5) 6.6 N

Answer: 3

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?

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.

Answer: 3

When a car goes around a circular curve on a level road,

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.

Answer: 3

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

1) straight down.
2) down and inwards.
3) down and outwards.
4) down and backwards.
5) down, inwards and backwards.

Answer: 3

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,

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.

Answer: 3