Study HubHubPage 39/118Scan verified MCQs with the answer highlighted, then open explanations when you want the reasoning.
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Kinematics
Speed of a body cannot be ________?
Speed is a scalar quantity representing how fast an object is moving and cannot be negative. It can be zero if the object is at rest, and it is always positive or zero.
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Thermodynamics
Which of the following is a path function?
Work and heat are path functions because their values depend on the specific path taken during a process, unlike state functions such as internal energy, enthalpy, and entropy which depend only on the state of the system.
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Magnetic Fields
Tesla is the unit for measuring:
Tesla (T) is the SI unit of magnetic flux density or magnetic induction, which measures the strength of a magnetic field. It is not used for magnetic intensity or magnetic moment.
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Vectors In A Plane
A vector can have a maximum of ________ components in a plane.
In a plane, a vector can be fully described by two components, typically along two perpendicular axes (e.g., x and y). Therefore, the maximum number of components a vector can have in a plane is two.
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Waves And Oscillations
The product of time period and frequency is ___________?
The product of the time period (T) and frequency (f) of a wave is always 1, since frequency is the reciprocal of the time period (f = 1/T). Therefore, T × f = 1, which is unity.
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Vector Addition
What is the minimum number of unequal magnitude vectors required to get a null vector?
To obtain a null (zero) vector by vector addition, at least three vectors of unequal magnitudes are required because two unequal vectors cannot cancel each other out completely. Three or more vectors can be arranged to sum to zero even if their magnitudes differ.
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Sound
The study of sound is called ___________?
The study of sound is called Acoustics, which deals with the production, transmission, and effects of sound waves. The other options are unrelated to the study of sound.
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Electric Motors
The back emf of a motor which is just started is ___________?
When a motor is just started, its rotor speed is zero, so the back emf, which depends on the rotor speed, is also zero. As the motor speeds up, the back emf increases.
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Circular Motion
An artificial satellite revolves around the Earth in a circular orbit. Which quantity remains constant?
In a circular orbit, an artificial satellite experiences a central gravitational force causing centripetal acceleration, but no external torque acts on it. Therefore, its angular momentum remains constant. Angular displacement and linear velocity change as the satellite moves, so they are not constant.
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Rotational Motion
The centripetal acceleration produced in a rotating body is commonly due to change in the ______ of the body?
Centripetal acceleration arises due to the continuous change in the direction of the velocity vector of a rotating body, even if its speed (magnitude) remains constant. Hence, it is caused by change in direction.