physics chapter 2/3

A projectile is thrown horizontally at 11.5 m/s. The projectile hits the ground 0.570 s later. What is the angle of impact the projectile makes with the horizontal ground?

-25.9°

A car is initially traveling west at 25 mph, and makes a turn north. As the car finishes the turn, its velocity is 20 mph north. It takes 3.5 seconds to complete the turn. What is the average acceleration of the car while it is turning, in mph/s? Let east be the positive-x direction and north be the positive-y direction.

-7.1i + 5.7j

An object moves 10 m east in 30 s and then returns to its starting point taking an additional 50 s. If west is chosen as the positive direction, what is the sign associated with the average velocity of the object?

0 (no sign)

A ball is rolled horizontally off a table with an initial speed of 0.24 m/s. A stop watch measures the ball's trajectory time from table to the floor to be 0.20 s. How far away from the table does the ball land? (g = 9.8 m/s2 and air resistance is negligible)

0.048 m

A bird, accelerating from rest at a constant rate, experiences a displacement of 25 m in 12 s. What is its acceleration?

0.35 m/s2

An object moves 10.0 m east in 10.0 s and then returns to its starting point taking an additional 40.0 s. If west is chosen as the positive direction, what is the average speed of the object?

0.4 m/s

A ball is rolled horizontally off a table with an initial speed of 0.24 m/s. A stopwatch measures the ball's trajectory time from table to the floor to be 0.36 s. What is the height of the table? (g = 9.8 m/s2 and air resistance is negligible)

0.64 m

A track star in the broad jump goes into the jump at 12.0 m/s and launches himself at 26.0° above the horizontal. How long is he in the air before returning to Earth? (g = 9.8 m/s2)

1.1 s

A mouse starts out in a corner of a room, and runs across the floor according to the following displacements: d1: 1.2i m + 0.4j m d2: 0.2i m - 0.8j m What is the magnitude of the total displacement of the mouse's position

1.5 m

A baseball is released at rest from the top of the Washington Monument. It hits the ground after falling for 5.85 s. What was the height from which the ball was dropped? (g = 9.80 m/s2 and assume air resistance is negligible)

1.68 × 102 m

At the top of a cliff 100 m high, Raoul throws a rock upward with velocity 15.0 m/s. How much later should he drop a second rock from rest so both rocks arrive simultaneously at the bottom of the cliff?

1.78 s

The highest mountain on Mars is Olympus Mons, rising 22 000 meters above the Martian surface. If we were to throw an object horizontally off the mountain top, how long would it take to reach the surface? (Ignore atmospheric drag forces and use gMars = 3.72 m/s2.)

1.8 minutes

A baseball thrown from the outfield is released from shoulder height at an initial velocity of 29.1 m/s at an initial angle of 30.0° with respect to the horizontal. What is the maximum vertical displacement that the ball reaches during its trajectory?

10.8 m

A string attached to an airborne kite is maintained at an angle of 44.0° with the horizontal. If a total of 160 m of string is reeled in while bringing the kite back to the ground, what is the horizontal displacement of the kite in the process? (Assume the kite string doesn't sag.)

115 m

An object moves at a constant velocity of 12 m/s to the southwest for an interval of 20 s. Halfway through this interval, what is the magnitude of its instantaneous velocity?

12 m/s

A vehicle designed to operate on a drag strip accelerates from zero to 34 m/s while undergoing a straight-line path displacement of 48 m. What is the vehicle's acceleration if its value may be assumed to be constant?

12 m/s2

In which of the following cases is the displacement's magnitude half the distance traveled?

12 steps east followed by 4 steps west

A ball is thrown vertically upwards at 24.5 m/s. For its complete trip (up and back down to the starting position), its average speed is

12.3 m/s.

A startled deer runs 520 m at 20.0° north of east for half a minute, then turns and runs 380 m at 55.0° north of west for 15.0 seconds and stops. What is the average velocity of the deer during this time?

12.4 m/s

A jogger runs halfway around a circular path with a radius of 60.0 m. What, respectively, are the magnitude of the displacement and the distance jogged?

120 m, 188 m

A ball is pushed downhill with an initial velocity of 3.0 m/s. The ball rolls down a hill with a constant acceleration of 1.6 m/s2. The ball reaches the bottom of the hill in 6.0 s. What is the ball's velocity at the bottom of the hill?

13 m/s

John throws a baseball from the outfield from shoulder height, at an initial velocity of 41.5 m/s at an initial angle of 40.0° with respect to the horizontal. The ball is in its trajectory for a total interval of 5.00 s before the third baseman catches it at an equal shoulder-height level. (Assume air resistance negligible.) What is the ball's horizontal displacement?

159 m

Human reaction time is usually about 0.18 s. If your lab partner holds a ruler between your finger and thumb and releases it without warning, how far can you expect the ruler to fall before you catch it? The nearest value is

16 cm

A ball is pushed with an initial velocity of 4.0 m/s. The ball rolls down a hill with a constant acceleration of 1.7 m/s2. The ball reaches the bottom of the hill in 7.0 s. What is the ball's velocity at the bottom of the hill?

16 m/s

An automobile driver puts on the brakes and decelerates from 35.0 m/s to zero in 11.0 s. What distance does the car travel?

193 m

A bird, accelerating from rest at a constant rate, experiences a displacement of 22 m in 10 s. What is the average velocity?

2.2 m/s

A Cessna aircraft has a lift-off speed of 135 km/h. What minimum constant acceleration does this require if the aircraft is to be airborne after a take-off run of 260 m?

2.70 m/s2

A truck moves 80.0 m east, then moves 140.0 m west, and finally moves east again a distance of 80.0 m. If east is chosen as the positive direction, what is the truck's resultant displacement?

20.0 m

A plane is moving due north, directly towards its destination. Its airspeed is 210 mph. A constant breeze is blowing from west to east at 20.0 mph. At what rate is the plane moving north?

209 mph

A boat moves at 10.8 m/s relative to the water. If the boat is in a river where the current is 2.00 m/s, how long does it take the boat to make a complete round trip of 1 100 m upstream followed by a 1 100-m trip downstream?

211 s

A stone is thrown with an initial speed of 11.5 m/s at an angle of 50.0 above the horizontal from the top of a 30.0-m-tall building. Assume air resistance is negligible, and g = 9.8 m/s2. What is the magnitude of the vertical-velocity component of the rock as it hits the ground?

25.8 m/s

A stone is thrown with an initial speed of 11.5 m/s at an angle of 50.0 above the horizontal from the top of a 30.0-m-tall building. Assume air resistance is negligible, and g = 9.8 m/s2. What is the magnitude of the horizontal displacement of the rock?

26.1 m

A stone is thrown with an initial speed of 11.5 m/s at an angle of 50.0 above the horizontal from the top of a 30.0-m-tall building. Assume air resistance is negligible, and g = 9.8 m/s2. What is the speed of the rock as it hits the ground?

26.8 m/s

Gwen releases a rock at rest from the top of a 40-m tower. If g = 9.8 m/s2 and air resistance is negligible, what is the speed of the rock as it hits the ground?

28 m/s

Wiley Coyote has missed the elusive road runner once again. This time, he leaves the edge of the cliff at 52.4 m/s horizontal velocity. If the canyon is 140 m deep, how far from his starting point at the edge of the cliff does the coyote land?

280 m

​Suppose a particle is moving along a straight line with a speed v for a time t, then stops for a time t, and then resumes moving along the original direction with speed v for time t. What has been the average speed of the particle for the total time period 3t?

2v/3

A speeding car traveling at a constant velocity of v passes a police car initially at rest beside the roadway. If the police car with constant acceleration of a immediately pursues the speeding car, how long is it before the police car is directly behind the speeding car?

2v/a

A bird, accelerating from rest at a constant rate, experiences a displacement of 25 m in 15 s. What is the final velocity after 15 s?

3.3 m/s

A European sports car dealer claims that his car will accelerate at a constant rate from rest to 100 km/h in 8.00 s. If so, what is the acceleration? (Hint: First convert speed to m/s.)

3.47 m/s2

Omar throws a rock down with speed 12.5 m/s from the top of a tower. The rock hits the ground after 1.50 s. What is the height of the tower? (air resistance is negligible)

30.0 m

A rock is thrown straight up with an initial velocity of 25.0 m/s. What maximum height will the rock reach before starting to fall downward? (Take acceleration due to gravity as 9.80 m/s2.)

31.9 m

A rock, released at rest from the top of a tower, hits the ground after 3.5 s. What is the speed of the rock as it hits the ground? (g = 9.8 m/s2 and air resistance is negligible)

34 m/s

A speeding car traveling at a constant velocity of 24 m/s passes a police care initially at rest beside the roadway. If the police car with constant acceleration of 3.0 m/s2 immediately pursues the speeding car, how far down the road does it draw even with the speeding car?

380 m

A quarterback takes the ball from the line of scrimmage, runs backward for 12 yards, then sideways parallel to the line of scrimmage for 18 yards. He then throws a 47-yard forward pass straight downfield perpendicular to the line of scrimmage. The receiver is tackled immediately. How far is the football displaced from its original position?

39 yards

Plane A is flying at 440 mph in the northeast direction relative to the Earth. Plane B is flying at 550 mph in the north direction relative to the Earth. What is the speed of Plane B as observed from Plane A?

392 mph

Mt. Everest is more than 8 000 m high. How fast would an object be moving if it could free fall to sea level after being released from an 8 000-m elevation? (Ignore air resistance.)

396 m/s

A boat travels upstream and after one hour has gone 10 km. The boat next travels downstream and after one hour has gone 18 km. If the boat's speed relative to the water is constant, what is the speed of the current in the river?

4 km/h

Maria throws two stones from the top edge of a building with a speed of 22 m/s. She throws one straight down and the other straight up. The first one hits the street in a time t1. How much later is it before the second stone hits?

4.5 s

Plane A is flying at 350 mph in the northeast direction relative to the Earth. Plane B is flying at 460 mph in the north direction relative to the Earth. What is the direction of motion of Plane B as observed from Plane A?

40.7° N of W

A rock is thrown straight down with an initial velocity of 14.3 m/s from a cliff. What is the rock's displacement after 2.0 s? (Acceleration due to gravity is 9.80 m/s2.)

48 m

A projectile is fired directly upwards at 49.4 m/s. A second projectile is dropped from rest at some higher elevation at the instant the first projectile is fired and passes the first projectile 3.00 s later. From the frame of reference of the first projectile, what is the velocity of the second projectile as it passes by?

49.4 m/s, downward

A baseball leaves the bat with a speed of 47 m/s and an angle of 45° above the horizontal. A 5.0-m-high fence is located at a horizontal distance of 137 m from the point where the ball is struck. Assuming the ball leaves the bat 1.0 m above ground level, by how much does the ball clear the fence?

49.7 m

A basketball player can jump 1.6 m off the hardwood floor. With what upward velocity did he leave the floor?

5.6 m/s

A cart is given an initial velocity of 5.0 m/s and experiences a constant acceleration of 2.4 m/s2. What is the magnitude of the cart's displacement during the first 5.0 s of its motion?

55 m

A ball is launched from ground level at 25 m/s at an angle of 31° above the horizontal. How far does it go before it is at ground level again?

56 m

A plane is moving due north, directly towards its destination. Its airspeed is 210 mph. A constant breeze is blowing from west to east at 25.0 mph. In which direction is the plane pointed?

6.79° W of N

Superguy is flying at treetop level near Paris when he sees the Eiffel Tower elevator start to fall (the cable snapped). His x-ray vision tells him Lois LaTour is inside. If Superguy is 1.00 km away from the tower, and the elevator falls from a height of 230 m, how long does Superguy have to save Lois, and what must be his average speed?

6.85 s, 150 m/s

A drag racer starts from rest and accelerates at 8.0 m/s2 for the entire distance of 300 m. What is the velocity of the race car at the end of the run?

69 m/s

A stone is thrown with an initial speed of 11.5 m/s at an angle of 50.0 above the horizontal from the top of a 30.0-m-tall building. Assume air resistance is negligible, and g = 9.8 m/s2. What is the magnitude of the horizontal-velocity component of the rock as it hits the ground?

7.39 m/s

A baseball player throws a ball straight up into the air. At a height of 3.00 m above the release point, the ball is moving at 1.25 m/s. What was the ball's initial speed?

7.77 m/s

A railroad train travels forward along a straight track at 90.0 m/s for 1 000 m and then travels at 70.0 m/s for the next 1 000 m. What is the average velocity?

78.8 m/s

A cheetah can maintain its maximum speed of 96.0 km/hr for 26.0 seconds. What minimum distance must a gazelle running 85.0 km/hr be ahead of the cheetah to escape?

79 m

A rifle is aimed horizontally toward the center of a target 120 m away. If the bullet strikes 11.2 cm below the center, what was the velocity of the bullet? (Ignore air friction.)

790 m/s

A European sports car dealer claims that his product will accelerate at a constant rate from rest to a speed of 100 km/h in 6.00 s. What distance will the sports car travel during the 6.00-s acceleration period? (Hint: First convert speed to m/s.)

83.3 m

A stone is thrown at an angle of 30° above the horizontal from the top edge of a cliff with an initial speed of 12 m/s. A stop watch measures the stone's trajectory time from top of cliff to bottom to be 4.8 s. What is the height of the cliff? (g = 9.8 m/s2 and air resistance is negligible)

84 m

A projectile is launched with speed v at an angle θ, the angle being less than 45º. What other angle would give the same range for this projectile launched at the same speed v?

90° - θ

A ball rolls down an incline, starting from rest. If the total time it takes to reach the end of the incline is T, how much time has elapsed when it is halfway down the incline?

> 0.5 T

An object moves along the x axis, with its position given by the function x(t) = ½ t3. Which of the following can be obtained from a graph of x vs. t?

All of the above

Two projectiles are launched at 100 m/s, the angle of elevation for the first being 30° and for the second 60°. Which of the following statements is false?

All of the above statements are true.

Two objects of different mass are released simultaneously from the top of a 20-m tower and fall to the ground. If air resistance is negligible, which statement best applies?

Both objects hit the ground together.

A hiker walks 200 m west and then walks 100 m north. In what direction is her resulting displacement?

None of the answers is correct.

A car is moving in the positive direction along a straight highway and accelerates at a constant rate while going from point A to point B. If the acceleration is positive, increasing the speed of the car, when does the position where the average speed equals the instantaneous speed occur during the time interval from A to B? Assume the time interval is T.

T/2 from the start of the interval

On a velocity-time graph for a particle, suppose the plot starts at some positive velocity and then follows a straight line to zero at a later time. Which of the following must be true about a position vs. time graph for this same time interval?

The curve will rise steeply at first and as time goes on will level out approaching its highest position value at the later time.

A v vs. t graph is drawn for a ball moving in one direction. The graph starts at the origin and at t = 5 s the acceleration of the ball is zero. We know that at t = 5 s,

The velocity of the ball is not changing.

Starting from rest, a car accelerates down a straight road with constant acceleration a for a time t, then the direction of the acceleration is reversed, (i.e., it is −a), and the car comes to a stop in an additional time t, the time for the whole trip being 2t. At what time, or times, is the average velocity of the car for the trip equal to its instantaneous velocity during the trip?

This occurs at 2 times, 0.5t and 1.5t

Two students are working on the same constant-acceleration problem involving a car undergoing constant acceleration, having started from rest and after a certain time having traveled a distance of 108 m. The students are to find the average velocity. Both students are required to show their work and round any intermediate answers as well as the final answer properly to 3 significant figures. Each rounded answer is to be used in the next step of calculation as they proceed. For the final answer, Student A uses the formula v​avg = (​xf - xi)/(tf - ti) getting the result 7.26 m/s, and Student B uses the formula v​avg = (v​0 + v)/2 getting the result 7.29 m/s. Assuming neither student makes a mistake, which student has the better answer?

Under significant figure rounding, both answers are equally as good.

Which formula is dimensionally consistent with an expression yielding a value for velocity? (a is acceleration, x is distance, and t is time)

at

A baseball is thrown by the center fielder (from shoulder level) to home plate where it is caught (on the fly at an equal shoulder level) by the catcher. At what point is the ball's speed at a minimum? (air resistance is negligible)

at the top of the trajectory

A baseball is thrown by the center fielder (from shoulder level) to home plate where it is caught (on the fly at shoulder level) by the catcher. At what point does the magnitude of the vertical component of velocity have its minimum value? (air resistance is negligible)

at the top of the trajectory

On a position-versus-time graph, the slope of the straight line joining two points on the plotted curve that are separated in time by the interval Δt, is which of the following quantities?

average velocity

A car is moving along a straight highway and accelerates at a constant rate while going from point A to point B. If the acceleration is positive, increasing the speed of the car, where does the position where the instantaneous speed equals the average speed occur for the interval from A to B?

closer to A than to B

In a two-dimensional Cartesian coordinate system the x-component of a given vector is equal to that vector's magnitude multiplied by which trigonometric function, with respect to the angle between vector and x-axis?

cosine

In a two-dimensional Cartesian coordinate system the y-component of a given vector is equal to that vector's magnitude multiplied by which trigonometric function, with respect to the angle between vector and y-axis?

cosine

In the case of constant acceleration, the average velocity equals the instantaneous velocity:

half-way through the time interval.

A projectile is launched at an angle less than 30° and at speed v. Which will increase the projectile's range more, ignoring atmospheric drag?

increasing the speed of launch by 50%

A plane is moving due north, directly towards its destination. Its airspeed is 220 mph. A constant breeze is blowing from west to east at 50 mph. How long will it take for the plane to travel 220 miles north?

more than one hour

A ball is thrown vertically upwards at 19.0 m/s. For its complete trip (up and back down to the starting position), its average velocity is:

not given.

The value of an object's acceleration may be characterized in equivalent words by which of the following?

rate of change of velocity

Which of the following is not a vector quantity?

temperature

A strobe photograph shows equally-spaced images of a car moving along a straight road. If the time intervals between images is constant, which of the following cannot be positive?

the acceleration of the car

A strobe photograph of a car moving along a straight road shows the interval between each successive image to be diminishing. If the direction of motion of the car is taken as positive, which of the following is/are negative?

the average acceleration of the car

An x vs. t graph is drawn for a ball moving in one direction. The graph starts at the origin and at t = 5 s the velocity of the ball is zero. We can be positive that at t = 5 s,

the ball has stopped.

A projectile is launched at an angle θ above the horizontal. Three seconds later the projectile is moving the same angle θ below the horizontal. Which of the following (actual values with units, not just algebraic symbols) can be found from the information given?

the initial vertical component of the projectile's velocity

The slope of the acceleration vs. time curve represents

the rate of change of acceleration.

A boat moves through the water in a river at a speed of 8 m/s relative to the water. The boat makes a trip downstream and then makes a return trip upstream to the original starting place. Which trip takes longer?

the upstream trip

If a is acceleration, v is velocity, x is position, and t is time, then which equation is not dimensionally correct?

v = a/t

Displacement is which of the following types of quantities?

vector

Consider the magnitude of the average speed, v​avg, speed, mag, and the magnitude of the average velocity, v​avg, velocity, mag, for the same trip. Which of the following is always true?

v​avg, speed, mag ≥ v​avg, velocity, mag

A change in a physical quantity w having initial value wi and final value wf is given by which of the following?

wf − wi

A baseball thrown from the outfield is released from shoulder height at an initial velocity of 28.3 m/s at an initial angle of 30.0° with respect to the horizontal. If it is in its trajectory for a total of 4.00 s before being caught by the third baseman at an equal shoulder-height level, what is the ball's net vertical displacement during its 4.00-s trajectory?

zero