Question 1

Omar throws a rock down with speed 12 m/s from the top of a tower.The rock hits the ground after 2.0 s.What is the height of the tower? (air resistance is negligible)
A)20 m
B)24 m
C)44 m
D)63 m

Accepted Answer

The answer of Omar throws a rock down with speed...

Question 2

John throws a rock down with speed 14 m/s from the top of a 30-m tower.If g = 9.8 m/s² and air resistance is negligible,what is the rock's speed just as it hits the ground? A)12 m/s B)28 m/s C)350 m/s D)784 m/s

Accepted Answer

Using the formula vf^2 = vi^2 + 2ad, we can find the final velocity of the rock just as it hits the ground.

vi = 14 m/s (initial velocity)
a = 9.8 m/s^2 (acceleration due to gravity)
d = 30 m (height of tower)

vf^2 = (14 m/s)^2 + 2(9.8 m/s^2)(30 m)
vf^2 = 196 + 588
vf^2 = 784
vf = sqrt(784) = 28 m/s

Therefore, the rock's speed just as it hits the ground is 28 m/s, which corresponds to choice B.

Question 3

In the case of constant acceleration,the average velocity equals the instantaneous velocity:
A)at the beginning of the time interval.
B)at the end of the time interval.
C)half-way through the time interval.
D)three-fourths of the way through the time interval.

Accepted Answer

When acceleration is constant, the average velocity is equal to the instantaneous velocity at the midpoint of the time interval. This is because, in uniform acceleration, the velocity changes linearly over time, making the average velocity (initial velocity + final velocity)/2 equal to the instantaneous velocity at the midpoint.

Question 4

A basketball player can jump 1.6 m off the hardwood floor.With what upward velocity did he leave the floor?
A)1.4 m/s
B)2.8 m/s
C)4.2 m/s
D)5.6 m/s

Accepted Answer

We can use the kinematic equation for vertical motion: 
Δy = v0t + 1/2at^2
where Δy is the vertical displacement (1.6 m), v0 is the initial velocity (what we're solving for), a is the acceleration (-9.8 m/s^2), and t is the time in the air. 
We know that at the highest point of the jump, the velocity is 0 m/s. Therefore, we can use the fact that the time to reach the highest point is half the total air time: 
t/2 = sqrt(2Δy/a)
t/2 = sqrt(2(1.6)/(-9.8))
t/2 = 0.357 s
Therefore, the total air time is: 
t = 2(0.357) = 0.714 s
Now we can solve for v0: 
Δy = v0t + 1/2at^2
1.6 = v0(0.714) + 1/2(-9.8)(0.714)^2
v0 = 5.6 m/s

Question 5

A baseball catcher throws a ball vertically upward and catches it in the same spot when it returns to his mitt.At what point in the ball's path does it experience zero velocity and non-zero acceleration at the same time?
A)midway on the way up
B)at the top of its trajectory
C)the instant it leaves the catcher's hand
D)the instant before it arrives in the catcher's mitt

Accepted Answer

At the top of its trajectory, the ball's velocity is momentarily zero as it changes direction from upward to downward motion. However, its acceleration is non-zero since it is still being acted upon by the force of gravity. This means that the ball is momentarily at rest, but still accelerating downwards. Therefore, the correct choice is B) at the top of its trajectory.

Question 6

A ball is thrown vertically upwards at 19.6 m/s.For its complete trip (up and back down to the starting position),its average speed is:
A)19.6 m/s.
B)9.80 m/s.
C)4.90 m/s.
D)not given.

Accepted Answer

When the ball is thrown upwards, it reaches a maximum height of h = (v^2)/(2g) = (19.6^2)/(2*9.8) = 19.6 meters.

The time taken to reach this height can be found using the formula t = v/g = 19.6/9.8 = 2 seconds.

The total time for the ball to complete its trip is therefore 2 + 2 = 4 seconds.

The distance travelled by the ball during this time is twice the maximum height, which is 2*19.6 = 39.2 meters.

Therefore, the average speed of the ball is distance/time = 39.2/4 = 9.8 m/s.

So, the best choice is B, which is 9.80 m/s.

Question 7

A water rocket,launched from the ground,rises vertically with acceleration of 30 m/s² for 1.0 s when it runs out of "fuel." Disregarding air resistance,how high will the rocket rise? A)15 m B)31 m C)61 m D)120 m

Accepted Answer

Using the kinematic equation:

h = ut + 1/2 at^2

where
u = initial vertical velocity = 0
a = acceleration = 30 m/s^2 (upward)
t = time = 1.0 s

Substituting the given values:

h = 0(1.0) + 1/2 (30) (1.0)^2
h = 15 m

Therefore, the rocket will rise 15 meters in the first second. However, since it has run out of fuel, it will continue to rise due to its initial velocity until it reaches the highest point of its trajectory. At that point, its velocity will be zero before it begins to fall back to the ground.

To find the maximum height reached by the rocket, we can use the fact that at the highest point of the trajectory, the final velocity will be zero. Therefore, using the kinematic equation:

v^2 = u^2 + 2as

where
v = final vertical velocity = 0
u = initial vertical velocity = 30 m/s (upward)
a = acceleration = -9.8 m/s^2 (downward, due to gravity)
s = displacement (which is equal to the maximum height reached)

Substituting the values:

0^2 = 30^2 + 2(-9.8) s
s = 61 meters

Therefore, the rocket will reach a maximum height of 61 meters.

The correct answer is choice C (61 m).

Question 8

A rock is thrown straight up with an initial velocity of 24.5 m/s.What maximum height will the rock reach before starting to fall downward? (Take acceleration due to gravity as 9.80 m/s². ) A)9.80 m B)19.6 m C)24.5 m D)30.6 m

Accepted Answer

The maximum height can be calculated using the formula: $ h = \frac{v^2}{2g} $, where $ v $ is the initial velocity and $ g $ is the acceleration due to gravity. Substituting the given values: $ h = \frac{(24.5)^2}{2 \times 9.8} = 30.6 $ m.

Question 9

A rock is thrown straight down with an initial velocity of 14.5 m/s from a cliff.What is the rock's displacement after 2.0 s? (Acceleration due to gravity is 9.80 m/s². ) A)28 m B)49 m C)55 m D)64 m

Accepted Answer

The answer of A rock is thrown straight down with...

Question 10

Maria throws two stones from the top edge of a building with a speed of 20 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? A)5 s B)4 s C)3 s D)Not enough information is given to work this problem.

Accepted Answer

The answer of Maria throws two stones from the top...

Question 11

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  getting the result 7.26 m/s,and Student B uses the formula  getting the result 7.29 m/s.Assuming neither student makes a mistake,which student has the better answer?
A)Student A
B)Student B
C)Under significant figure rounding,both answers are equally as good.
D)The described result cannot happen;this is physics after all.

Accepted Answer

The answer of Two students are working on the same...

Question 12

A rock is thrown straight up with an initial velocity of 19.6 m/s.What time interval elapses between the rock's being thrown and its return to the original launch point? (Acceleration due to gravity is 9.80 m/s². ) A)4.00 s B)5.00 s C)8.00 s D)10.0 s

Accepted Answer

The time to reach the highest point is given by t = v/g = 19.6 m/s / 9.8 m/s² = 2 s. The total time for the round trip is twice this, so 2 * 2 s = 4 s.

Question 13

A baseball is released at rest from the top of the Washington Monument.It hits the ground after falling for 6.0 s.What was the height from which the ball was dropped? (g = 9.8 m/s² and assume air resistance is negligible) A)1.5 x 10² m B)1.8 x 10² m C)1.1 x 10² m D)2.1 x 10² m

Accepted Answer

The height can be calculated using the formula $ h = \frac{1}{2} g t^2 $. Substituting $ g = 9.8 \, \text{m/s}^2 $ and $ t = 6.0 \, \text{s} $, we get $ h = \frac{1}{2} \times 9.8 \times 36 = 176.4 \, \text{m} $, which is approximately $ 1.8 \times 10^2 \, \text{m} $.

Question 14

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? A)28 m/s B)30 m/s C)56 m/s D)784 m/s

Accepted Answer

The speed of the rock can be calculated using the formula v = √(2gh), where g is the acceleration due to gravity and h is the height. Substituting the given values, v = √(2 * 9.8 * 40) = 28 m/s.

Question 15

A rock,released at rest from the top of a tower,hits the ground after 1.5 s.What is the speed of the rock as it hits the ground? (g = 9.8 m/s² and air resistance is negligible) A)15 m/s B)20 m/s C)31 m/s D)39 m/s

Accepted Answer

The answer of A rock,released at rest from the top...

Question 16

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?
A)The greater mass hits the ground first.
B)Both objects hit the ground together.
C)The smaller mass hits the ground first.
D)No conclusion can be made with the information given.

Accepted Answer

According to the law of free fall, all objects near the surface of the Earth fall with the same acceleration due to gravity. Therefore, the time it takes for both objects to reach the ground will be the same, regardless of their masses. Neglecting air resistance, both objects will hit the ground at the same time.

Question 17

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 8000-m elevation? (Ignore air resistance. )
A)396 m/s
B)120 m/s
C)1 200 m/s
D)12 000 m/s

Accepted Answer

The final velocity of an object in free fall can be calculated using the formula v=sqrt(2gh), where g is the acceleration due to gravity (9.8 m/s^2), h is the height from which the object is dropped, and sqrt represents the square root function. If we plug in 8000 m for h, we get v=sqrt(2*9.8*8000)=396 m/s. Therefore, the correct choice is A.

Question 18

Human reaction time is usually about 0.20 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:
A)4.0 cm.
B)9.8 cm.
C)16 cm.
D)20 cm.

Accepted Answer

The answer of Human reaction time is usually about 0.20...

Question 19

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?
A)5.05 s
B)3.76 s
C)2.67 s
D)1.78 s

Accepted Answer

The answer of At the top of a cliff 100...

Question 20

A parachutist jumps out of an airplane and accelerates with gravity to a maximum velocity of 58.8 m/s in 6.00 seconds.She then pulls the parachute cord and after a 4.00-second constant deceleration,descends at 10.0 m/s for 60.0 seconds,reaching the ground.From what height did the parachutist jump?
A)914 m
B)1 130 m
C)1 520 m
D)1 750 m

Accepted Answer

The correct answer is A.The parachutist accelerates with gravity to a maximum velocity of 58.8 m/s in 6.00 seconds. So, the acceleration due to gravity is:a = (58.8 m/s) / (6.00 s) = 9.80 m/s^2The parachutist then pulls the parachute cord and after a 4.00-second constant deceleration, descends at 10.0 m/s for 60.0 seconds, reaching the ground. So, the deceleration is:a = (10.0 m/s - 58.8 m/s) / (4.00 s) = -12.2 m/s^2The height from which the parachutist jumped is:h = (1/2) * (58.8 m/s + 10.0 m/s) * (60.0 s) = 914 m

Quiz 2: Motion in One Dimension

Omar throws a rock down with speed 12 m/s from the top of a tower.The rock hits the ground after 2.0 s.What is the height of the tower? (air resistance is negligible)

John throws a rock down with speed 14 m/s from the top of a 30-m tower.If g = 9.8 m/s² and air resistance is negligible,what is the rock's speed just as it hits the ground?

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

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

A baseball catcher throws a ball vertically upward and catches it in the same spot when it returns to his mitt.At what point in the ball's path does it experience zero velocity and non-zero acceleration at the same time?

A ball is thrown vertically upwards at 19.6 m/s.For its complete trip (up and back down to the starting position) ,its average speed is:

A water rocket,launched from the ground,rises vertically with acceleration of 30 m/s² for 1.0 s when it runs out of "fuel." Disregarding air resistance,how high will the rocket rise?

A rock is thrown straight up with an initial velocity of 24.5 m/s.What maximum height will the rock reach before starting to fall downward? (Take acceleration due to gravity as 9.80 m/s². )

A rock is thrown straight down with an initial velocity of 14.5 m/s from a cliff.What is the rock's displacement after 2.0 s? (Acceleration due to gravity is 9.80 m/s². )

Maria throws two stones from the top edge of a building with a speed of 20 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?

A rock is thrown straight up with an initial velocity of 19.6 m/s.What time interval elapses between the rock's being thrown and its return to the original launch point? (Acceleration due to gravity is 9.80 m/s². )

A baseball is released at rest from the top of the Washington Monument.It hits the ground after falling for 6.0 s.What was the height from which the ball was dropped? (g = 9.8 m/s² and assume air resistance is negligible)

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?

A rock,released at rest from the top of a tower,hits the ground after 1.5 s.What is the speed of the rock as it hits the ground? (g = 9.8 m/s² and air resistance is negligible)

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?

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 8000-m elevation? (Ignore air resistance. )

Human reaction time is usually about 0.20 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:

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?

A parachutist jumps out of an airplane and accelerates with gravity to a maximum velocity of 58.8 m/s in 6.00 seconds.She then pulls the parachute cord and after a 4.00-second constant deceleration,descends at 10.0 m/s for 60.0 seconds,reaching the ground.From what height did the parachutist jump?

Quiz 2: Motion in One Dimension

Omar throws a rock down with speed 12 m/s from the top of a tower.The rock hits the ground after 2.0 s.What is the height of the tower? (air resistance is negligible)

John throws a rock down with speed 14 m/s from the top of a 30-m tower.If g = 9.8 m/s2 and air resistance is negligible,what is the rock's speed just as it hits the ground?

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

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

A baseball catcher throws a ball vertically upward and catches it in the same spot when it returns to his mitt.At what point in the ball's path does it experience zero velocity and non-zero acceleration at the same time?

A ball is thrown vertically upwards at 19.6 m/s.For its complete trip (up and back down to the starting position) ,its average speed is:

A water rocket,launched from the ground,rises vertically with acceleration of 30 m/s2 for 1.0 s when it runs out of "fuel." Disregarding air resistance,how high will the rocket rise?

A rock is thrown straight up with an initial velocity of 24.5 m/s.What maximum height will the rock reach before starting to fall downward? (Take acceleration due to gravity as 9.80 m/s2. )

A rock is thrown straight down with an initial velocity of 14.5 m/s from a cliff.What is the rock's displacement after 2.0 s? (Acceleration due to gravity is 9.80 m/s2. )

Maria throws two stones from the top edge of a building with a speed of 20 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?

A rock is thrown straight up with an initial velocity of 19.6 m/s.What time interval elapses between the rock's being thrown and its return to the original launch point? (Acceleration due to gravity is 9.80 m/s2. )

A baseball is released at rest from the top of the Washington Monument.It hits the ground after falling for 6.0 s.What was the height from which the ball was dropped? (g = 9.8 m/s2 and assume air resistance is negligible)

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?

A rock,released at rest from the top of a tower,hits the ground after 1.5 s.What is the speed of the rock as it hits the ground? (g = 9.8 m/s2 and air resistance is negligible)