IB Physics

### A ball is whirled on a string, then the string breaks. What causes the ball to move off in a straight line?

inertia

### When an object experiences uniform circular motion, the direction of the net force is

is directed toward the center of the circular path

### A pilot executes a vertical dive then follows a semi circular arc until it is going straight up. Just as the plane is at its lowest point, the force on him is

more than mg, and pointing up

### A stone, of mass m, is attached to a strong string and whirled in a vertical circle of radius r. At the exact bottom of the path, the tension in the string is 3 times the stone's weight. the stone's speed at this point is given by

(2gr)^1/2

### a roller coaster car is on a track that forms a circular loop in the vertical plane if the car is to just maintain contact with track at the top of the loop, what is the minimum value for its centripetal acceleration at this point/

g downward

### a roller coaster car (mass=M) is on a track that forms a circular loop (radius=r) in the vertical plane. if the car is to just maintain contact with the track at the top of the loop, what is the minimum value for its speed at that point?

(rg)^1/2

### the movement of an object or a point mass at a constant speed around a circle that has a fixed radius is called uniform:

circular motion

### what is the term for the net force directed toward the center of an object's circular path?

centripetal force

### the maximum speed around a level curve is 30.0km/h. what is the maximum speed around a curve with twice the radius? (assume all other factors remain unchanged)

42.4 km/h

### when an object experiences uniform circular motion, the direction of the acceleration is

directed toward the center of the circular path

### which of the following can be a centripetal force?

all of the above (tension, friction, and gravity)

### a car is moving with a constant speed v around a level curve. the coefficient of friction between the tires and the road is 0.40. what is the minimum radius of the curve if the car is to stay on the road?

2.5v²/g

### a 100 kg ball is attached to a string of 0.50m and swung in a horizontal circle with a velocity of 2.00 m/s. find the centripetal acceleration

8.0 m/s²

### a car of mass m goes around a banked curve of radius r with speed v. if the road is frictionless due to ice, the car can still negotiate the curve if the horizontal component of the normal force on the car from the road is equal in magnitude to

mv²/r

### a car goes around a curve of radius r at a constant speed v. then it goes around the same curve at half of the original speed. what is the centripetal force on the car as it goes around curve for the second time, compared to the first time?

one fourth as big

### consider a particle moving with constant speed such that its acceleration of constant magnitude is always perpendicular to its velocity

it is moving in a circle

### a car goes around a curve of radius r at a constant speed v. then it goes around a curve of radius 2r at speed 2v. what is the centripetal force on the car as it goes around the second curve, compared to the first?

twice as big

### what type of acceleration does an object moving with constant speed in a circular path experience?

centripetal acceleration

### when a car makes a sharp left turn, what causes the passengers to move toward the right side of the car?

centrifugal force

### an object moves in a circular path at a constant speed. compare the direction of the object's velocity and acceleration vectors

the vectors are perpendicular

### a car goes around a curve of radius r at a constant speed v. what is the direction of the net force on the car?

toward the curve's center

### when an object is moving with uniform circular motion, the object's tangential speed

is perpendicular to the plane of motion

### a coin of mass m rests on a turntable a distance r from the axis of rotation. the turntable rotates with a frequency of f. what is the minimum coefficient of static friction between the turntable and the coin if the coin is not to slip?

(4π²f²r)/g

### when an object is moving with uniform circular motion, the centripetal acceleration of the object is

directed toward the center of motion

### a stone of mass m is attached to a strong string and whirled in a vertical circle of radius r. at the exact top of the path the tension in the string is 3 times the stone's weight. the stone's speed at this point is given by

2(gr)∧½

### is it possible for an object moving with a constant speed to accelerate? explain.

yes although the speed is constant the direction of the velocity can be changing