Question 1

The time needed for a car whose speed is 60 km/h to travel 800 m is
A) 0.48 min.
B) 0.8 min.
C) 4.5 min.
D) 13 min.

Accepted Answer

First, we need to convert the speed of 60 km/h to meters per second.

60 km/h = 60000 m/3600 s = 16.67 m/s

Then, we can use the formula:

time = distance/speed

time = 800 m/16.67 m/s

time ≈ 48 seconds

Finally, we convert the time in seconds to minutes:

time = 48 s/60 = 0.8 min

Therefore, the answer is B) 0.8 min.

Question 2

The idea that all conclusions about the natural world must be based upon experiment and observation was first emphasized in the work of
A) Aristotle.
B) St. Thomas Aquinas.
C) Galileo.
D) Newton.

Accepted Answer

The idea that all conclusions about the natural world must be based upon experiment and observation was first emphasized in the work of Galileo. He played a major role in the Scientific Revolution of the 17th century and emphasized the importance of empirical evidence in understanding the natural world.

Question 3

A car starts from a speed of 10 m/s with an acceleration of 2 m/s². The time needed for the car to reach 30 m/s is A) 10 s. B) 20 s. C) 30 s. D) 40 s.

Accepted Answer

The formula to calculate the time needed to reach a certain speed with a constant acceleration is $t = \frac{v_f - v_i}{a}$, where $v_f$ is the final velocity, $v_i$ is the initial velocity, and $a$ is the acceleration. Substituting the given values, $t = \frac{30 m/s - 10 m/s}{2 m/s^2} = 10 s$.

Question 4

A ship travels 20 km to the south and then 40 km to the west. The ship's displacement from its starting point is
A) 20 km.
B) 40 km.
C) 45 km.
D) 60 km.

Accepted Answer

The ship has traveled 20 km to the south and 40 km to the west, forming a right-angled triangle. The displacement is the shortest distance between the starting point and the ending point, which is the hypotenuse of the triangle. Using the Pythagorean theorem, we can calculate the length of the hypotenuse:
c^2 = a^2 + b^2
c^2 = 20^2 + 40^2
c^2 = 400 + 1600
c^2 = 2000
c = sqrt(2000)
c ≈ 44.72

Therefore, the ship's displacement from its starting point is approximately 45 km.

Question 5

A snail travels 45 cm in 20 min. Its average speed is
A) 2.25 cm/h.
B) 15 cm/h.
C) 90 cm/h.
D) 135 cm/h.

Accepted Answer

The answer of A snail travels 45 cm in 20...

Question 6

Which one or more of the following pairs of displacements cannot be added to give a resultant displacement of 2 m?
A) 1 m and 1 m.
B) 1 m and 2 m.
C) 1 m and 3 m.
D) 1 m and 4 m.

Accepted Answer

The displacement of 1 m and 4 m cannot be added together to give a resultant displacement of 2 m because the sum of the two displacements is 5 m, which is greater than 2 m. The other pairs of displacements, 1 m and 1 m, 1 m and 2 m, and 1 m and 3 m, can be added together to give a resultant displacement of 2 m.

Question 7

A ball thrown upward at 30 m/s will reach the ground after about
A) 1.0 s.
B) 2.0 s.
C) 6.0 s.
D) 8.0 s.

Accepted Answer

To determine the time it takes for a ball thrown upward to reach the ground, we can use the formula for the time of flight under gravity, ignoring air resistance. The formula is $ t = \frac{2v}{g} $, where $ v $ is the initial velocity and $ g $ is the acceleration due to gravity (approximately $ 9.8 \, m/s^2 $). Plugging in the given values, $ t = \frac{2 \times 30}{9.8} \approx 6.12 $ seconds. Rounding to the nearest whole number gives us approximately 6 seconds.

Question 8

A stone dropped from a cliff reaches the ground in 4 s. The stone's speed is then
A) 10 m/s.
B) 40 m/s.
C) 196 m/s.
D) 392 m/s.

Accepted Answer

The speed of the stone can be calculated using the formula v = gt, where g is the acceleration due to gravity (approximately 9.8 m/s^2) and t is the time in seconds. Thus, v = 9.8 m/s^2 * 4 s = 39.2 m/s, which is approximately 40 m/s.

Question 9

A stone is thrown upward from a roof at the same time as another, identical stone is dropped from there. The two stones
A) reach the ground at the same time.
B) have the same speed when they reach the ground.
C) have the same acceleration when they reach the ground.
D) None of the choices are correct.

Accepted Answer

Both stones experience the same gravitational acceleration throughout their motion, which is approximately 9.8 m/s² downward, regardless of their initial velocities.

Question 10

A ball thrown upward at 30 m/s will continue to rise for about rev:
A) 0.5 s.
B) 1.0 s.
C) 3.0 s.
D) 4.0 s.

Accepted Answer

The time a ball takes to reach its highest point when thrown upwards can be calculated using the formula $t = \frac{v}{g}$, where $v$ is the initial velocity (30 m/s) and $g$ is the acceleration due to gravity (approximately 9.8 m/s$^2$). Plugging in the values, $t = \frac{30}{9.8} \approx 3.06$ seconds, which rounds to about 3.0 seconds.

Question 11

In 6 min a person running at 10 km/h covers a distance of
A) 167 m.
B) 600 m.
C) 1000 m.
D) 1667 m.

Accepted Answer

The answer of In 6 min a person running at...

Question 12

The minimum number of unequal forces whose vector sum can equal zero is
A) 2.
B) 3.
C) 4.
D) 5.

Accepted Answer

This is a well-known concept in physics called the "triangle rule." If we have two vectors, we can always create a triangle with those vectors as two sides, and the third side of the triangle will be the vector sum. Therefore, we need at least three vectors (forces) to form a closed triangle and for the vector sum to equal zero.

Question 13

Which of the following sets of displacements might be able to return a car to its starting point?
A) 2, 8, 10, and 25 km.
B) 5, 20, 35, and 65 km.
C) 60, 120, 180, and 240 km.
D) 100, 100, 100, and 400 km.

Accepted Answer

For a car to return to its starting point, the total displacement in any direction must be equal to the total displacement in the opposite direction. In option C, the sum of the displacements (60 + 120 + 180 + 240 km) can be arranged such that the car moves in one direction and then back in the opposite direction for the same total distance, allowing it to return to its starting point. For example, moving 240 km in one direction and then 60, 120, and 180 km back in the opposite direction totals 360 km each way.

Question 14

A car moving at 15 m/s comes to a stop in 3 s. Its acceleration is A) -0.2 m/s². B) -5 m/s². C) -15 m/s². D) -45 m/s².

Accepted Answer

We can use the equation of motion:
v = u + at
where v is the final velocity (0 m/s), u is the initial velocity (15 m/s), a is the acceleration, and t is the time taken to come to a stop (3 s).

Rearranging the equation, we get:
a = (v - u) / t
a = (0 - 15) / 3
a = -5 m/s^2

Therefore, the acceleration of the car is -5 m/s^2, which is option B.

Question 15

A car starts from rest and reaches a speed of 15 m/s in 10s. Its acceleration is A) 0.67 m/s². B) 1.5 m/s². C) 6.7 m/s². D) 15 m/s².

Accepted Answer

Acceleration (a) = (final velocity (v) - initial velocity(u))/time(t)
Here, initial velocity (u) = 0 m/s
final velocity (v) = 15 m/s
time (t) = 10 s
Therefore, a = (15-0)/10 = 1.5 m/s^2
Hence, the correct answer is B.

Question 16

A car whose speed is a steady 50 km/h
A) cannot be accelerated.
B) is accelerated when it climbs a hill.
C) is accelerated when it descends a hill.
D) is accelerated when it climbs a hill, goes over the crest, and descends on the other side.

Accepted Answer

Acceleration refers to any change in velocity, which includes changes in speed or direction. When a car climbs a hill, goes over the crest, and descends, its direction changes, indicating acceleration even if the speed remains constant.

Question 17

A boat whose velocity through the water is 20 km/h is moving in a river whose current is 6 km/in relative to the riverbed. The velocity of the boat relative to the riverbed must be between
A) 6 and 20 km/h.
B) 6 and 26 km/h.
C) 12 and 20 km/h.
D) 12 and 26 km/h.

Accepted Answer

The velocity of the boat relative to the riverbed can be calculated by adding or subtracting the velocity of the river's current from the boat's velocity through the water. When moving downstream, the boat's velocity relative to the riverbed is the sum of its own velocity and the current's velocity (20 km/h + 6 km/h = 26 km/h). When moving upstream, the boat's velocity relative to the riverbed is its velocity minus the current's velocity (20 km/h - 6 km/h = 14 km/h). Therefore, the boat's velocity relative to the riverbed must be between 14 and 26 km/h.

Question 18

Which of the following units could be associated with a vector quantity? A) km/s². B) kg/s. C) hours. D) m³.

Accepted Answer

Vector quantities have both magnitude and direction. Acceleration, which is a vector quantity, can be measured in km/s².

Question 19

An airplane reaches its takeoff speed of 60 m/s in 30 s starting from rest. The time it spends in going from 40 m/s to 60 m/s is
A) 10 s.
B) 15 s.
C) 20 s.
D) 25 s.

Accepted Answer

The airplane accelerates uniformly from 0 to 60 m/s in 30 seconds, so its acceleration is $60 \, \text{m/s} / 30 \, \text{s} = 2 \, \text{m/s}^2$. To find the time to accelerate from 40 m/s to 60 m/s, use the formula $v = u + at$, where $v$ is the final velocity (60 m/s), $u$ is the initial velocity (40 m/s), $a$ is the acceleration (2 m/s$^2$), and $t$ is the time. Solving for $t$, we get $t = (v - u) / a = (60 - 40) / 2 = 20 / 2 = 10$ seconds.

Question 20

Ball A is thrown horizontally and ball B is thrown upward.
A) Ball A has the greater downward acceleration.
B) Ball B has the greater downward acceleration.
C) They have the same downward acceleration.
D) Neither has any downward acceleration.

Accepted Answer

Both balls experience the same acceleration due to gravity, which is a constant 9.8 m/s² downward. The direction of their motion (horizontal or vertical) does not affect the acceleration due to gravity. Therefore, they have the same downward acceleration.

Quiz 2: Motion

The time needed for a car whose speed is 60 km/h to travel 800 m is

The idea that all conclusions about the natural world must be based upon experiment and observation was first emphasized in the work of

A car starts from a speed of 10 m/s with an acceleration of 2 m/s2. The time needed for the car to reach 30 m/s is

A ship travels 20 km to the south and then 40 km to the west. The ship's displacement from its starting point is

A snail travels 45 cm in 20 min. Its average speed is

Which one or more of the following pairs of displacements cannot be added to give a resultant displacement of 2 m?

A ball thrown upward at 30 m/s will reach the ground after about

A stone dropped from a cliff reaches the ground in 4 s. The stone's speed is then

A stone is thrown upward from a roof at the same time as another, identical stone is dropped from there. The two stones

A ball thrown upward at 30 m/s will continue to rise for about rev:

In 6 min a person running at 10 km/h covers a distance of

The minimum number of unequal forces whose vector sum can equal zero is

Which of the following sets of displacements might be able to return a car to its starting point?

A car moving at 15 m/s comes to a stop in 3 s. Its acceleration is

A car starts from rest and reaches a speed of 15 m/s in 10s. Its acceleration is

A car whose speed is a steady 50 km/h

A boat whose velocity through the water is 20 km/h is moving in a river whose current is 6 km/in relative to the riverbed. The velocity of the boat relative to the riverbed must be between

Which of the following units could be associated with a vector quantity?

An airplane reaches its takeoff speed of 60 m/s in 30 s starting from rest. The time it spends in going from 40 m/s to 60 m/s is

Ball A is thrown horizontally and ball B is thrown upward.

A car starts from a speed of 10 m/s with an acceleration of 2 m/s². The time needed for the car to reach 30 m/s is