1.
The SI base unit used to measure mass is the
Correct Answer
C. Kilogram
Explanation
The SI base unit used to measure mass is the kilogram. Mass is a fundamental property of matter and is measured using the kilogram as the base unit. The kilogram is defined as the mass of the International Prototype of the Kilogram, a platinum-iridium cylinder kept at the International Bureau of Weights and Measures in France. It is a standard unit of mass that is widely used in scientific and everyday measurements.
2.
Which of the following units is the SI unit of velocity?
Correct Answer
B. Meter per second
Explanation
The SI unit of velocity is meter per second. Velocity is defined as the rate of change of displacement with respect to time, and it is measured in meters per second. This unit represents the distance traveled in meters divided by the time taken in seconds, which gives the speed of an object in a particular direction.
3.
The graph above describes the motion of a cyclist. The graph illustrates that the acceleration of the cyclist
Correct Answer
B. Increases
Explanation
The graph above shows the motion of a cyclist. From the graph, we can see that the velocity of the cyclist is increasing over time. Since acceleration is the rate of change of velocity, an increasing velocity indicates that the acceleration of the cyclist is also increasing. Therefore, the correct answer is "increases".
4.
On a speed-time graph, a line with a negative slope indicates that the object is
Correct Answer
B. Slowing down
Explanation
A line with a negative slope on a speed-time graph indicates that the object is slowing down. The slope of a line on a graph represents the rate of change, and in this case, a negative slope means that the speed is decreasing over time. This indicates that the object is decelerating or slowing down its motion.
5.
Which straight-line acceleration indicates an increase in speed?
Correct Answer
C. 4 m/s2
Explanation
An acceleration of 4 m/s2 indicates an increase in speed because acceleration is the rate at which an object's velocity changes. A positive acceleration value means that the velocity is increasing, while a negative acceleration value indicates a decrease in velocity. Therefore, an acceleration of 4 m/s2 suggests that the object is gaining speed.
6.
A pitcher throws a baseball to home plate, a distance of 60.5 ft. The ball reaches home plate in 0.63 s. What is the velocity of the ball?
Correct Answer
D. 96 ft/s toward home plate
Explanation
The velocity of the ball is 96 ft/s toward home plate because velocity is calculated by dividing the distance traveled by the time taken. In this case, the ball traveled a distance of 60.5 ft in 0.63 s, resulting in a velocity of 96 ft/s. The "toward home plate" part is included in the answer to specify the direction of the velocity.
7.
Moving from 0 m/s to 25 m/s in 8.0 s equals an average acceleration of
Correct Answer
D. 3.1 m/s^2
Explanation
The average acceleration can be calculated by dividing the change in velocity by the time taken. In this case, the change in velocity is 25 m/s (from 0 m/s to 25 m/s) and the time taken is 8.0 s. Dividing 25 m/s by 8.0 s gives an average acceleration of 3.1 m/s^2.
8.
A cheetah can accelerate at up to 6.0 m/s^{2}. How long does it take for a cheetah to speed up from 10.5 m/s to 12.2 m/s?
Correct Answer
A. 0.28 s
Explanation
The cheetah's acceleration is given as 6.0 m/s^2. To find the time it takes for the cheetah to speed up from 10.5 m/s to 12.2 m/s, we can use the equation v = u + at, where v is the final velocity, u is the initial velocity, a is the acceleration, and t is the time. Rearranging the equation to solve for time, we have t = (v - u) / a. Plugging in the values, we get t = (12.2 - 10.5) / 6.0 = 0.28 s.
9.
On a distance vs. time graph, the line of an object at rest is a
Correct Answer
B. Flat line with a slope of zero.
Explanation
The line of an object at rest on a distance vs. time graph is a flat line with a slope of zero because when an object is at rest, it does not change its position over time. Therefore, the distance traveled remains constant, resulting in a horizontal line on the graph. The slope of this line is zero because there is no change in distance with respect to time.
10.
The difference between speed and velocity is that velocity includes
Correct Answer
A. Direction.
Explanation
The difference between speed and velocity lies in the inclusion of direction. While speed only refers to the rate at which an object moves, velocity takes into account both the speed and the direction in which the object is moving. Therefore, velocity provides a more comprehensive description of an object's motion, as it specifies both the magnitude and the direction of the object's displacement.