The change in the kinetic energy refers to the work done in displacing a body, thus, the change in the kinetic energy of an object refers to the work done on the object.
The correct formula to use is:
W = Initial kinetic energy - Final kinetic energy;
Where, W = change in kinetic energy
Final kinetic energy and initial kinetic energy = 1/2 MV^2
Initial velocity = 15 m/s
Final velocity = 13.5 m/s
Initial mass = 0.650 kg
Final mass = 0.950 kg
W = 1/2 [0.650* (15 *15)] - 1/2 [0.950 * (13.5 * 13.5)]
W = 146.25 - 173.13 = 26.88
Therefore, the change in kinetic energy is 26.88 J.
The negative sign has to be ignored, because change in kinetic energy can not be negative.
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Answer:
C) 50 m/s
Explanation:
With the given information we can calculate the acceleration using the force and mass of the box.
Newton's 2nd Law: F = ma
- 5 N = 1 kg * a
- a = 5 m/s²
List out known variables:
- v₀ = 0 m/s
- a = 5 m/s²
- v = ?
- Δx = 250 m
Looking at the constant acceleration kinematic equations, we see that this one contains all four variables:
Substitute known values into the equation and solve for v.
- v² = (0)² + 2(5)(250)
- v² = 2500
- v = 50 m/s
The final velocity of the box is C) 50 m/s.
C) above, the Earth's core is about the melting point of iron.
