when to use kinematics, energy conservation equations

[Rosalindbungs]

hi! can anybody help me distinguish when to use which equation?

especially when they give a psg that has deltay, velocity and are asking for something like the time.

example: passage 4 chapter Work and energy of physics part 1 book? page 159 number 25. they use the kinematics instead of Ei=Ef

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[Rabolisk]

In general both are applicable. However, energy is scalar and force, velocity, and acceleration are vectors.

 

[lorenzomicron]

If you are concerned only about the start and finish conditions, then you can use energy, given that you have enough information. sometimes to use energy, you first have to use kinetics to find out more information.

if you are concerned about things happening in between, kinematic must be used.