1.
Which of the following is a physical quantity that has a magnitude but no direction?
Correct Answer
D. Scalar
Explanation
A scalar is a physical quantity that only has a magnitude, meaning it can be described by a numerical value alone without any reference to direction. Unlike vectors, which have both magnitude and direction, scalars represent quantities such as mass, temperature, or time that do not have a specific orientation or direction associated with them. Therefore, the correct answer is scalar.
2.
Multiplying or dividing vectors by scalars results in
Correct Answer
D. Vectors
Explanation
When multiplying or dividing vectors by scalars, the result is always a vector. This is because multiplying a vector by a scalar scales the magnitude of the vector without changing its direction, resulting in a new vector. Similarly, dividing a vector by a scalar also scales the magnitude of the vector, but in the opposite direction, still resulting in a vector. Therefore, the correct answer is vectors.
3.
Identify the following quantities as scalar or vector: the mass of an object, the number of leaves on a tree, and wind velocity.
Correct Answer
C. Scalar, scalar, vector
Explanation
The mass of an object is a scalar quantity because it only has magnitude and no direction. The number of leaves on a tree is also a scalar quantity as it only represents a count and does not have any direction associated with it. Wind velocity, on the other hand, is a vector quantity because it has both magnitude (speed) and direction (the direction in which the wind is blowing).
4.
Which of the following is an example of a vector quantity?
Correct Answer
B. Velocity
Explanation
Velocity is an example of a vector quantity because it has both magnitude and direction. In physics, vectors are quantities that require both a numerical value and a specific direction to fully describe them. Velocity, specifically, represents the rate at which an object changes its position and includes information about the object's speed as well as the direction it is moving in. Therefore, velocity satisfies the criteria of a vector quantity.
5.
Which of the following is a physical quantity that has both magnitude and direction?
Correct Answer
A. Vector
Explanation
A vector is a physical quantity that has both magnitude and direction. It represents quantities such as displacement, velocity, and force. Magnitude refers to the size or quantity of the vector, while direction indicates its orientation in space. Unlike scalars, which only have magnitude, vectors require both magnitude and direction to completely describe them. A frame of reference is a coordinate system used to describe the position and motion of objects, while a resultant is the sum or combination of multiple vectors. However, only a vector possesses both magnitude and direction.
6.
Which of the following is always positive?
Correct Answer
B. Magnitude
Explanation
Magnitude refers to the size or quantity of a vector or scalar quantity. It is always positive or zero. Scalars are quantities that are fully described by their magnitude (e.g., speed), while vectors have both magnitude and direction (e.g., velocity). The term "direction" doesn't inherently have a numerical value, and it's the orientation of a vector rather than a quantity with a positive or negative value.
7.
Identify the following quantities as scalar or vectors: the speed of a snail, the time it takes to run a mile, and the free-fall acceleration.
Correct Answer
B. Scalar, scalar, vector
Explanation
The speed of a snail is a scalar quantity because it only has magnitude and no direction. The time it takes to run a mile is also a scalar quantity as it only represents a duration and has no direction. On the other hand, free-fall acceleration is a vector quantity as it has both magnitude (9.8 m/sÂ²) and direction (downwards towards the center of the Earth).
8.
An ant on a picnic table travels 3.0*10^1 cm eastward, then 25 cm northward, and finally 15 cm westward. What is the magnitude of the ant's displacement relative to its original position?
Correct Answer
A. 29.15 cm
Explanation
.
9.
For the winter, a duck flies 10.0 m/s due south against a gust of wind with a speed of 2.5 m/s. What is the resultant velocity of the duck?
Correct Answer
C. 7.5 m/s south
Explanation
The duck is flying south at a speed of 10.0 m/s, while the gust of wind is blowing north at a speed of 2.5 m/s. Since the gust of wind is against the duck's motion, it acts as a negative force. To find the resultant velocity, we subtract the wind speed from the duck's speed. Therefore, the resultant velocity of the duck is 7.5 m/s south.
10.
In a coordinate system, a vector is oriented at an angle with respect to the x-axis. The y-component of the vector equals the vector's magnitude multiplied by which trigonometric function?
Correct Answer
C. Sin θ
Explanation
In a coordinate system, when a vector forms an angle θ with the x-axis, its y-component equals the vector's magnitude multiplied by the sine of that angle (Sin θ). This relationship arises from trigonometry and is fundamental in determining the vertical component of a vector's magnitude in relation to its angle with the x-axis.
11.
In a coordinate system, a vector is oriented at an angle with respect to the x-axis. The x-component of the vector equals the vector's magnitude multiplied by which trigonometric function?
Correct Answer
B. Cos θ
Explanation
The x-component of a vector in a coordinate system is found by multiplying the magnitude of the vector by the cosine of the angle it makes with the x-axis. This is because the cosine function relates the adjacent side of a right triangle (which represents the x-component) to the hypotenuse (which represents the magnitude of the vector). Therefore, the correct answer is cos θ.
12.
Which of the following is the motion of objects moving in two dimensions under the influence of gravity?
Correct Answer
D. Projectile motion
Explanation
Projectile motion refers to the motion of objects that are launched into the air and move in two dimensions under the influence of gravity. It involves both vertical and horizontal velocities, as the object follows a curved path known as a projectile trajectory. The directrix is not relevant to this concept. Therefore, the correct answer is projectile motion.
13.
Which of the following does not exhibit parabolic motion?
Correct Answer
C. A flat piece of paper is released from a window.
Explanation
A flat piece of paper does not exhibit parabolic motion because it lacks the necessary force or propulsion to follow a curved trajectory. Unlike the other options, which involve objects being thrown or propelled with force, the paper simply falls due to gravity without any initial velocity or additional force acting upon it. As a result, its motion is purely vertical and does not follow a parabolic path.
14.
What is the path of a projectile (in the absence of air resistance)?
Correct Answer
D. A parabola
Explanation
In the absence of friction, the path of a projectile follows a parabolic trajectory. This is because the only force acting on the projectile is gravity, which causes it to accelerate downward. As a result, the projectile follows a curved path that is symmetric around its highest point. This trajectory is known as a parabola.
15.
Which of the following is not an example of projectile motion?
Correct Answer
C. A hot-air balloon drifting toward Earth.
Explanation
A hot-air balloon drifting toward Earth is not an example of projectile motion because it does not have an initial horizontal velocity. In projectile motion, an object is launched with an initial velocity and then follows a curved path due to the influence of gravity. The volleyball, baseball, and long jumper all have an initial horizontal velocity and are subject to gravity, causing them to follow a curved trajectory. However, a hot-air balloon does not have an initial horizontal velocity and is carried by wind currents, resulting in a more vertical descent rather than a curved path.
16.
Which of the following exhibits parabolic motion?
Correct Answer
C. A stone is thrown into a lake
Explanation
A stone thrown into a lake exhibits parabolic motion because it follows a curved path due to the combination of its initial horizontal velocity and the downward force of gravity. As the stone moves forward, gravity pulls it downward, causing it to curve downward in a parabolic trajectory. This motion is characteristic of objects that are launched with an initial velocity and experience a constant force acting vertically downward, resulting in a parabolic path.
17.
Which of the following is an example of projectile motion?
Correct Answer
B. A thrown baseball
Explanation
A thrown baseball is an example of projectile motion because it follows a curved path in the air due to the combined effects of its initial velocity and the force of gravity acting on it. As soon as the baseball leaves the pitcher's hand, it becomes subject to the force of gravity, causing it to follow a parabolic trajectory until it eventually lands on the ground. This type of motion, where an object is launched into the air and moves under the influence of gravity alone, is known as projectile motion.
18.
Which of the following is a coordinate system for specifying the precise location of objects in space?
Correct Answer
C. Frame of reference
Explanation
A coordinate system is a method used to define the position of objects in space. In this context, a frame of reference serves as a coordinate system that allows for the precise location of objects to be specified. It provides a set of axes, such as the x-axis and y-axis, which can be used to measure distances and determine positions accurately. By using a frame of reference, objects can be located and described based on their position relative to a fixed point or set of points, enabling precise spatial calculations and measurements.
19.
A piece of chalk is dropped by a teacher walking at a speed of 1.5 m/s. From the teacher's perspective, the chalk appears to fall
Correct Answer
A. Straight down
Explanation
From the teacher's perspective, the chalk appears to fall straight down because the teacher is walking at a constant speed and in a straight line. Since there are no external forces acting on the chalk horizontally, it will continue to move forward with the same speed as the teacher. However, gravity will cause it to accelerate vertically downwards, resulting in a straight downward fall from the teacher's point of view.
20.
A passenger on a bus moving east sees a man standing on a curb. From the passenger's perspective, the man appears to
Correct Answer
A. Move west at a speed that is equal to the bus's speed.
Explanation
The passenger on the bus sees the man on the curb appear to move west at a speed that is equal to the bus's speed. This is because the bus is moving east, so the relative motion between the bus and the man is that the man appears to be moving in the opposite direction at the same speed as the bus.