What is the kinetic energy of an object with a mass of #5 kg# that has been in freefall for #8 s#?

Answer 1

#15.366kJ#

Assuming the object has fallen from rest near earth, we may use the equations of motion for constant acceleration to find its velocity after 8 seconds :

#v=u+at#

#=0+(9,8)(8)#

#=78,4m//s#

Hence its kinetic energy at this stage is

#E_k=1/2mv^2#

#=1/2xx5xx78.4^2#

#=15,366kJ#

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Answer 2

Xavier Adame

The kinetic energy of the object can be calculated using the formula:

Kinetic energy (KE) = 1/2 * mass * velocity^2

In freefall, the velocity of the object can be calculated using the equation of motion:

velocity = acceleration * time

Given that the object is in freefall near the surface of the Earth, we can use the acceleration due to gravity, which is approximately 9.8 m/s^2.

Substituting the values into the equation, we get:

velocity = 9.8 m/s^2 * 8 s = 78.4 m/s

Now, we can calculate the kinetic energy:

KE = 1/2 * 5 kg * (78.4 m/s)^2

KE ≈ 1/2 * 5 kg * 6155.36 m^2/s^2

KE ≈ 15438.4 J

Therefore, the kinetic energy of the object is approximately 15438.4 joules.

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Answer from HIX Tutor

When evaluating a one-sided limit, you need to be careful when a quantity is approaching zero since its sign is different depending on which way it is approaching zero from. Let us look at some examples.