Question 1

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 answer of A rock is thrown straight up with...

Question 2

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 fall towards the Earth with the same acceleration, regardless of their mass. Therefore, both objects will reach the ground at the same time, regardless of their mass. Therefore, both objects will hit the ground together.

Question 3

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

Since both stones experience the same acceleration due to gravity, the time it takes for each stone to hit the ground is the same. Therefore, the second stone will hit the ground t₁ seconds after the first stone, which is 4 seconds later (since t₁ = 5 seconds). Thus, the answer is choice B.

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: 
Δy = v0Δt + (1/2)gt^2
where Δy is the displacement (1.6 m), v0 is the initial velocity (what we're solving for), Δt is the time in the air (unknown), and g is the acceleration due to gravity (-9.8 m/s^2).

Solving for v0, we get:
v0 = (Δy - (1/2)gt^2) / Δt
v0 = (1.6 - (1/2)(-9.8)t^2) / t

We know that the time in the air is the same as the time it takes to reach the maximum height, which occurs at the halfway point of the jump (0.8 m above the floor).

Using the kinematic equation:
Δy = v0Δt + (1/2)gt^2
0.8 = v0(t/2) + (1/2)(-9.8)(t/2)^2
0.8 = v0(t/2) - 1.225t^2

Solving for t, we get:
t = 0.4 seconds

Plugging in t = 0.4 seconds into our v0 equation, we get:
v0 = (1.6 - (1/2)(-9.8)(0.4)^2) / 0.4
v0 = 5.6 m/s

Therefore, the answer is D) 5.6 m/s.

Question 5

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 * 10² m B)1.8 * 10² m C)1.1 * 10² m D)2.1 * 10² m

Accepted Answer

The answer of A baseball is released at rest from...

Question 6

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

We can use the formula h = vi*t + 1/2*a*t^2, where h is the height of the tower, vi is the initial velocity (12 m/s downwards), t is the time it takes to hit the ground (2 s), and a is the acceleration due to gravity (-9.8 m/s^2 downwards). 
Plugging in the values, we get: 
h = (12 m/s)*(2 s) + 1/2*(-9.8 m/s^2)*(2 s)^2 
h = 24 m - 19.6 m 
h = 4.4 m

However, this is the height from where the rock was thrown, not the height of the tower. To find the height of the tower, we need to add the height from where the rock was thrown (which we assume is the top of the tower) to the height we calculated. 
Therefore, h_tower = h + 0 (since we assume the top of the tower is where the rock was thrown from) 
h_tower = 4.4 m + 40 m (height of the rock when it hits the ground) 
h_tower = 44 m

Therefore, the best choice is C, with a height of 44 m.

Question 7

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 answer of Gwen releases a rock at rest from...

Question 8

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

At the highest point of the trajectory, the ball's velocity is 0 m/s. Therefore, the ball's average speed for the entire trip is equal to twice the speed at the highest point of its trajectory when it is at the starting position.

The speed at the highest point of the trajectory can be found using the fact that the vertical component of velocity at any point in the trajectory is given by:

v = v0 - gt

where v is the velocity, v0 is the initial velocity, g is the acceleration due to gravity (9.8 m/s^2), and t is the time.

At the highest point of the trajectory, the velocity is 0, so we can rearrange the equation to solve for the time it takes to reach that point:

0 = 19.6 m/s - 9.8 m/s^2 * t
t = 2.0 s

Therefore, the ball takes a total of 4.0 s (2.0 s up and 2.0 s down) to complete its trip, and its average speed is:

average speed = total distance / total time

The total distance is twice the distance traveled on the way up, which can be found using the kinematic equation:

y = v0t - 1/2gt^2

where y is the displacement, t is the time, and v0 is the initial velocity.

y = (19.6 m/s)(2.0 s) - 1/2 (9.8 m/s^2)(2.0 s)^2
y = 19.6 m

Therefore, the total distance is 2(19.6 m) = 39.2 m.

The average speed is then:

average speed = 39.2 m / 4.0 s
average speed = 9.8 m/s

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

Question 9

A ball of relatively low density is thrown upwards.Because of air resistance the acceleration while traveling upwards is -10.8 m/s².On its trip downward the resistance is in the opposite direction and the resulting acceleration is -8.8 m/s².When the ball reaches the level from which it was thrown, how does its speed compare to that with which it was thrown? A)It is greater than the original speed upward. B)It is the same as the original speed upward. C)It is less than the original speed upward. D)Without knowing the original speed, this problem cannot be solved.

Accepted Answer

The ball experiences a greater resistance force while traveling upwards than downwards (10.8 m/s^2 versus 8.8 m/s^2). This means that the net downward acceleration is greater than the net upward acceleration, so the ball loses more velocity during its upward trip than it gains during its downward trip. Therefore, when the ball reaches the level from which it was thrown, its speed is less than its original speed upward.

Question 10

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 answer of A parachutist jumps out of an airplane...

Question 11

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 changes direction and thus experiences zero velocity. However, since the ball is still accelerating due to the force of gravity, it experiences non-zero acceleration at the same time.

Question 12

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 v^2 = u^2 + 2gs, where u = 14 m/s, g = 9.8 m/s^2 (acceleration due to gravity), and s = 30 m (height of tower), we can calculate the final velocity of the rock just as it hits the ground:

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

Therefore, the best choice is B) 28 m/s.

Question 13

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 answer of A rock is thrown straight up with...

Question 14

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 15

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 16

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

First, we need to find the velocity of the rocket at the end of its 1 second of powered flight. We know that acceleration (a) is 30 m/s^2 and time (t) is 1.0 s. So, using the equation v = u + at, where initial velocity (u) is 0 m/s, we get:
v = u + at
v = 0 + (30 m/s^2)(1.0 s)
v = 30 m/s

Next, we can use the equation for displacement (s) to find how high the rocket will rise. Again, initial velocity (u) is 0 m/s, and we can use the velocity (v) we just calculated as the final velocity. So:
s = (v^2 - u^2) / (2a)
s = (30 m/s)^2 / (2 * 30 m/s^2)
s = 900 / 60
s = 15 m

Therefore, the rocket will rise to a height of 15 meters.

Question 17

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 18

Starting from rest, a car accelerates down a straight road with constant acceleration a₁ for a time t₁, then the acceleration is changed to a different constant value a₂for an additional time t₂.The total elapsed time is t₁ + t₂.Can the equations of kinematics be used to find the total distance traveled? A)No, because this is not a case of constant acceleration. B)Yes, use (a₁ + a₂)/2 as the average acceleration and the total time in the calculation. C)Yes, use a₁ + a₂ as the acceleration and the average time (t₁ + t₂)/2 in the calculation. D)Yes, break the problem up into 2 problems, one with the conditions for the first time interval and the other with the conditions for the second time interval, noting that for the second time interval the initial velocity is that from the end of the first time interval.When done, add the distances from each of the time intervals.

Accepted Answer

The equations of kinematics can be used to find the total distance traveled by breaking up the problem into two problems, one for each time interval. In the first problem, the car starts from rest and accelerates with constant acceleration a₁ for time t₁, finding the distance traveled during this time interval. In the second problem, the car continues with a different constant acceleration a₂ for time t₂, starting from the final velocity from the first time interval. The distance traveled during the second time interval is calculated. Finally, the total distance traveled is found by adding the distances found in both time intervals.

Question 19

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...

Question 20

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 velocity of an object in free fall is given by the formula v=sqrt(2gh), where v is velocity, g is the acceleration due to gravity (9.8 m/s^2), and h is the height. Substituting the values, we get v=sqrt(2*9.8*8000) = 396 m/s. Therefore, the correct choice is A.

Quiz 2: Motion in One Dimension

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.)

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?

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

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)

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)

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 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 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 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?

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 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.)

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 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?

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 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)

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.)

Quiz 2: Motion in One Dimension

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.)

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?

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

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)