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# CHEM 305 Lecture 2: SEA DIPLOMAExam

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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 polar vector.
Velocity maybe regarded as 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

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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 have 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

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b) 15N and 25N
c) 10N and 15N
d) 20N and 5N
Explanation: P = 3x and Q = 5x R = 35N θ = 120°
R = √(P2+ R2+ 2PQcosθ)
35 = 7x or x = 35/7 = 5
P = 15N Q = 25N
9. Walking of 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.
1. For motion in two or three dimensions, what is the angle between velocity and acceleration vectors?
a) 0°
b) 180°
c) Between 0° and 180°
d) 90°