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Which of the following describes the 'Work-Energy Theorem' correctly?
Work done equals change in potential energy
Work done equals change in kinetic energy
Work done is zero at constant velocity
Work done is proportional to time taken
Work done equals change in kinetic energy
The Work-Energy Theorem states that the net work done by all forces acting on an object is equal to the change in its kinetic energy. This principle applies regardless of whether the force is constant or variable.
The Work-Energy Theorem states that the net work done by all forces acting on an object is equal to the change in its kinetic energy. This principle applies regardless of whether the force is constant or variable.
Think of pushing a shopping cart: the work you apply with your hands translates directly into the speed (kinetic energy) of the cart.
W = ╬Ф K (Work equals change in Kinetic energy).
WnetтАЛ=╬ФK=KfтАЛтИТKiтАЛ=21тАЛm(vf2тАЛтИТvi2тАЛ) тАФ Work-Energy Theorem expression
W=FтЛЕsтЛЕcos(╬╕) тАФ General definition of work
According to Newton's second law, FnetтАЛ=mтЛЕa. By substituting a=tvfтАЛтИТviтАЛтАЛ and integrating W=тИлFтЛЕdx, we derive W=21тАЛmvf2тАЛтИТ21тАЛmvi2тАЛ. This confirms that work acts as a mechanism for energy transfer to or from an object, manifesting as a change in the speed of the body.
Work done by net force is positive if speed increases.
Work done by net force is negative if speed decreases (e.g., braking).
The theorem is valid for both linear and curvilinear motion.
Internal forces do not contribute to the change in the system's total kinetic energy.
Simplifies complex problems by focusing on energy states rather than vector-based force-acceleration calculations.
Does not provide information about the time duration or path taken.
Calculating stopping distance of a vehicle based on brake force.
Determining the velocity of an object sliding down a frictionless ramp.
The theorem assumes a frame of reference where Newton's laws are valid (inertial frames).
Option A refers to the Principle of Conservation of Mechanical Energy for conservative forces, not the general Work-Energy theorem.
Option C is incorrect because work done is zero at constant velocity ONLY if the net force is zero; however, work is not universally zero.
Option D is false as work is independent of the time interval taken to perform the action.
B is correct тАФ The Work-Energy Theorem establishes that the total work done on an object is strictly equivalent to the change in its kinetic energy.
Always verify if the question asks for 'Net Work' or 'Work by a specific force'; the theorem specifically requires 'Net Work' (sum of all forces) to equate to the change in kinetic energy.