# Engineering Physics Questions and Answers – Scalar and Vector

This set of Engineering Physics Multiple Choice Questions & Answers (MCQs) focuses on “Scalar and Vector”.

1. The quantity which has the only magnitude is called ____________
a) A scalar quantity
b) A vector quantity
c) A chemical quantity
d) A magnitude quantity

Explanation: A quantity which has only magnitude and no direction is called scalar quantity. Example: mass

2. Force is a vector quantity.
a) True
b) False

Explanation: Force has both magnitude and direction. A quantity that has both magnitude and direction is called a vector quantity. Therefore, force is a vector quantity.

3. A polar vector is one which?
a) Gives the position of an object
b) Tells how much and in which direction an object has changed its position
c) Represents rotational effect
d) Has a starting point of application

Explanation: The vector which has a starting point or a point of application is called a polar vector. Velocity may be regarded as a polar vector.

4. Which of the following acts in accordance with right hand screw rule?
a) Polar vector
b) Axial vector
c) Displacement vector
d) Position vector

Explanation: The vectors which represent rotational effect and act along the axis of rotation in accordance with right hand screw rule are called axial vector. Axial vector will have its direction along its axis of rotation depending on its anticlockwise or clockwise rotational effect.

5. What is the magnitude of a unit vector?
a) It has no magnitude
b) Zero
c) Constant but not zero
d) Unity

Explanation: The magnitude of a unit vector is unity. It just gives the direction of a vector. A unit vector has no units or dimensions.

6. Which of the following has zero magnitude?
a) Fixed vector
b) Zero vector
c) Modulus of a vector
d) Unit vector

Explanation: A zero or null vector is a vector that has zero magnitude and an arbitrary direction. The velocity vector of a stationary object is a zero vector.

7. Flying a bird is an example of ____________
a) Collinear vector
b) Multiplication of vector
d) Composition of vector

Explanation: When a bird flies, it pushes the air with force in the downward direction with its wings. In accordance with Newton’s law of motion, the air exerts equal and opposite reaction. According to the parallelogram law, the resultant of the reaction acts on the birds in the upward direction and helps the bird to fly upwards.

8. Two forces whose magnitudes are in ratio of 3:5 give a resultant of 35N. If the angle of inclination is 60°, calculate the magnitude of each force.
a) 15N and35N
b) 15N and 25N
c) 10N and 15N
d) 20N and 5N

Explanation: P = 3x and Q = 5x R = 35N θ = 120°
R = $$\sqrt{P^2 + R^2 + 2PQcosθ}$$
35 = 7x or x = 35/7 = 5
P = 15N Q = 25N.

9. Walking off a man is an example of ____________
a) Resolution of forces
c) Subtraction of vectors
d) Multiplication of vectors

Explanation: While walking, a person presses the ground with his feet slightly slanted in the backward direction. The ground exerts upon him an equal and opposite reaction. Its horizontal component enables the person to move forward while the vertical component balances this weight.

Sanfoundry Global Education & Learning Series – Engineering Physics.

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