Physics 111 Exam 1 Practice

True/False A purely vertical slope means an infinite speed

True

A skateboarder, starting from rest, rolls down a 14.9-m ramp. When she arrives at the bottom of the ramp her speed is 7.24 m/s. (a) Determine the magnitude of her acceleration, assumed to be constant. (b) If the ramp is inclined at 32.0 ° with respect to the ground, what is the component of her acceleration that is parallel to the ground?

(a) 1.75 m/s^2 (b) 1.48 m/s^2

Your friend has slipped and fallen. To help her up, you pull with a force , as the drawing shows. The vertical component of this force is 130 newtons (N), while the horizontal component is 116 N. Find (a) the magnitude of and (b) the angle .

(a) 174 N (b) 48.2 °

An ocean liner leaves New York City and travels 15.9 ° north of east for 206 km. How far east and how far north has it gone? In other words, what are the magnitudes of the components of the ship's displacement vector in the directions (a) due east and (b) due north?

(a) 198.1 km (b) 56.4 km

A sprinter explodes out of the starting block with an acceleration of +2.34 m/s2, which she sustains for 1.35 s. Then, her acceleration drops to zero for the rest of the race. What is her velocity at (a)t = 1.35 s and (b) at the end of the race?

(a) 3.16 m/s (b) 3.16 m/s

A bicyclist in the Tour de France has a speed of 27.0 miles per hour (mi/h) on a flat section of the road. What is this speed in (a) kilometers per hour (km/h), and (b) meters per second (m/s)?

(a) 43.5 km/h (b) 12.07 m/s

Two skaters, a man and a woman, are standing on ice. Neglect any friction between the skate blades and the ice. The mass of the man is 85 kg, and the mass of the woman is 66 kg. The woman pushes on the man with a force of 55 N due east. Determine the acceleration (magnitude and direction) of (a) the man and (b) the woman.

(a) A man = 0.65 m/s^s due east (b) A woman = 0.83 m/s^2 due west

A ball is thrown vertically upward, which is the positive direction. A little later it returns to its point of release. The ball is in the air for a total time of 7.51 s. What is its initial velocity? Neglect air resistance.

+36.8 m/s

You are driving into St. Louis, Missouri, and in the distance you see the famous Gateway-to-the-West arch. This monument rises to a height of 192 m. You estimate your line of sight with the top of the arch to be 7.19 ° above the horizontal. Approximately how far (in kilometers) are you from the base of the arch?

1.52 km

The moon is a satellite that orbits the earth at a radius of 3.85 × 108 m. The mass of the earth is 5.98 × 1024 kg. What is the orbital speed of the moon?

1017.8 m/s

A computer is reading data from a rotating CD-ROM. At a point that is 0.0173 m from the center of the disk, the centripetal acceleration is 233 m/s2. What is the centripetal acceleration at a point that is 0.0880 m from the center of the disc?

1185 m/s^2

During takeoff, an airplane climbs with a speed of 150 m/s at an angle of 36 degrees above the horizontal. The speed and direction of the airplane constitute a vector quantity known as the velocity. The sun is shining directly overhead. How fast is the shadow of the plane moving along the ground? (That is, what is the magnitude of the horizontal component of the plane's velocity?)

121.35 m/s

A motorcycle is traveling up one side of a hill and down the other side. The crest of the hill is a circular arc with a radius of 40.6 m. Determine the maximum speed that the cycle can have while moving over the crest without losing contact with the road.

19.95 m/s

A person looking out the window of a stationary train notices that raindrops are falling vertically down at a speed of 5.75 m/s relative to the ground. When the train moves at a constant velocity, the raindrops make an angle of 25° when they move past the window, as the drawing shows. How fast is the train moving?

2.68 m/s

A meteoroid is speeding through the atmosphere, traveling east at 15.1 km/s while descending at 14.1 km/s. What is its speed, in km/s?

20.7 km/s

At some airports there are speed ramps to help passengers get from one place to another. A speed ramp is a moving conveyor belt on which you can either stand or walk. Suppose a speed ramp has a length of 109 m and is moving at a speed of 2.4 m/s relative to the ground. In addition, suppose you can cover this distance in 74 s when walking on the ground. If you walk at the same rate with respect to the speed ramp that you walk on the ground, how long does it take for you to travel the 109 m using the speed ramp?

28.2 s

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 82.7 m/s and centripetal acceleration of 2.26 g (2.26 times the acceleration due to gravity) are displayed. Determine the radius of the turn (in meters).

308.8 m

In the amusement park ride known as Magic Mountain Superman, powerful magnets accelerate a car and its riders from rest to 45.4 m/s in a time of 7.16 s. The mass of the car and riders is 5.05 × 103 kg. Find the average net force exerted on the car and riders by the magnets.

32017 N

A fire hose ejects a stream of water at an angle of 31.0 ° above the horizontal. The water leaves the nozzle with a speed of 29.4 m/s. Assuming that the water behaves like a projectile, how far from a building should the fire hose be located to hit the highest possible fire?

38.8 m

An airplane has a mass of 3.20 × 104 kg and takes off under the influence of a constant net force of 1.55 × 104 N. What is the net force that acts on the plane's 81.8-kg pilot?

39.6 N

Due to continental drift, the North American and European continents are drifting apart at an average speed of about 3 cm per year. At this speed, how long (in years) will it take for them to drift apart by another 1209 m?

40300 years

The greatest height reported for a jump into an airbag is 99.4 m by stuntman Dan Koko. In 1948 he jumped from rest from the top of the Vegas World Hotel and Casino. He struck the airbag at a speed of 39 m/s (88 mi/h). To assess the effects of air resistance, determine how fast he would have been traveling on impact had air resistance been absent.

44.1 m/s

A horizontal rifle is fired at a bull's-eye. The muzzle speed of the bullet is 690 m/s. The gun is pointed directly at the center of the bull's-eye, but the bullet strikes the target 0.024 m below the center. What is the horizontal distance between the end of the rifle and the bull's-eye?

47.61 m

A jet is taking off from the deck of an aircraft carrier, as the Figure shows. Starting from rest, the jet is catapulted with a constant acceleration of +34.0 m/s2 along a straight line and reaches a velocity of +63.0 m/s. Find the displacement of the jet.

58.4 m

At an instant when a soccer ball is in contact with the foot of the player kicking it, the horizontal or x component of the ball's acceleration is 910 m/s2 and the vertical or y component of its acceleration is 800 m/s2. The ball's mass is 0.48 kg. What is the magnitude of the net force acting on the soccer ball at this instant?

581.6 N

The Space Shuttle travels at a speed of about 6.06 x 103 m/s. The blink of an astronaut's eye lasts about 92.0 ms. How many football fields (length = 91.4 m) does the Space Shuttle cover in the blink of an eye?

6.10

A woman stands on a scale in a moving elevator. Her mass is 60.0 kg, and the combined mass of the elevator and scale is an additional 809 kg. Starting from rest, the elevator accelerates upward. During the acceleration, the hoisting cable applies a force of 9120 N. What does the scale read (in N) during the acceleration?

629.7 N

In diving to a depth of 465 m, an elephant seal also moves 580 m due east of his starting point. What is the magnitude of the seal's displacement?

743.4 m

For a standard production car, the highest road-tested acceleration ever reported occurred in 1993, when a Ford RS200 Evolution went from zero to 26.8 m/s (60 mi/h) in 3.175 s. Find the magnitude of the car's acceleration.

8.44 m/s^2

A space laboratory is rotating to create artificial gravity, as the figure indicates. Its period of rotation is chosen so that the outer ring (rO = 2440 m) simulates the acceleration due to gravity on earth (9.80 m/s2). What should be the radius rI of the inner ring, so it simulates the acceleration due to gravity on the surface of Mars (3.72 m/s2)?

926.2 m

True/False When an astronaut is in orbit around the earth, she is weightless?

False

True/False Newton's 3rd Law is about inertia

False 3rd law: every action has an equal and opposite reaction

True/False The Pythagorean theorem is the relationship between 2 sides of a right triangle

False Relationship between 3 sides of a right triangle

True/False Speed is a vector

False Speed is a magnitude

True/False If the net force on an object is zero, it will slow down and eventually stop.

False The object will keep moving if no force is acting on it

True/False An object thrown horizontally from a tall building hits sooner than if dropped.

False The objects will hit at the same time

True/False You can subtract vectors

False You can add a positive vector to a negative one but not subtract

True/False Weight and Inertia both have units of Newtons.

False inertia has units of grams or kilograms

True/False If something always has a constant velocity, then it can still accelerate.

False Acceleration is the change in velocity over time

True/False While standing still, on a sloped surface, your weight is canceled by the normal force.

False The forces are not acting in the same axis so they can't cancel each other out

True/False Because of the t-squared, x = xo + vot + (1/2)at2 is valid if "a" changes in time.

False acceleration must remain constant

True/False The D = Vt equation is only valid if acceleration is a constant.

False (only valid if a=0)

True/False A scalar is a pure number and not a vector

True

True/False If there is no friction, then a special velocity must be at work

True

True/False It is possible to accelerate towards a certain point in space but never actually get there.

True

True/False Objects with a lot of inertia resist change as they move

True

True/False Slope is equal to speed

True

True/False The Moon travels at a constant speed, but is accelerating in its orbit around the Earth.

True

True/False The Vf2 = Vi2 + 2a(∆R) equation is only valid if acceleration is a constant.

True

True/False The formula x = xo + vot + (1/2)at2 describes the position of an object, if it's moving, and if it's accelerating

True

True/False The parent formulas are only valid if acceleration is constant

True

True/False There is a force of gravity between every object

True

True/False If something always has a constant speed, then it can still accelerate.

True

The space station in the drawing is rotating to create artificial gravity. The speed of the inner ring is one half that of the outer ring. As an astronaut walks from the inner to the outer ring, what happens to her apparent weight? a. Her apparent weight becomes twice as great. b. Her apparent weight becomes half as great. c. Her apparent weight becomes one-fourth as great. d. Her apparent weight does not change. e. Her apparent weight becomes four times as great.

a. Her apparent weight becomes twice as great.

A satellite is in a circular orbit around a planet. A second satellite is placed in a different circular orbit that is farther away from the same planet. How do the speeds of the two satellites compare? a. The speed of the second satellite is less than the speed of the first satellite. b. The speeds of the two satellites are equal. c. The speed of the second satellite is greater than the speed of the first satellite.

a. The speed of the second satellite is less than the speed of the first satellite.

A boat moves 3.0 km due north and then moves 1.0 km due south. The time for this trip is half an hour. What is the average velocity of the boat? a. 2.0 km/h, due south b. 4.0 km/h, due north c. 8.0 km/h d. 8.0 km/h, due north e. 4.0 km/h

b. 4.0 km/h, due north

The two shorter sides of a right triangle have lengths 9.88 meters and 4.65 meters. What is the length of the hypotenuse?

c = 10.92m

When the outdoor emergency warning siren at Cheryl's school was tested, the sound from the siren took 7.0 s to reach her house located 2.40 km from the school. What is the speed of sound in air? a. 640 m/s b. 240 m/s c. 340 m/s d. 440 m/s e. 540 m/s

c. 340 m/s

A certain object is in equilibrium. Which one of the following statements is not true? a. object has no acceleration. b. The object has a constant velocity. c. The object must be at rest. d. No net force acts on the object.

c. The object must be at rest

In a right triangle, the side opposite angle has length 2.37 meters and the hypotenuse has length 7.72 meters. What is the sine of the angle?

sin θ = 0.307