What is the total mechanical energy of a 3 kg object traveling at 7 m/s if its potential energy is 42 J?
A. 247.8 J
B. 73.5 J
C. 115.5 J
D. 31.5 J
The total mechanical energy (E) of an object is the sum of its kinetic energy (KE) and potential energy (PE).
Given:
Mass (m) = 3 kg
Velocity (v) = 7 m/s
Potential energy (PE) = 42 J
The kinetic energy (KE) is given by the formula:
KE = (1/2) * m * v^2
Substituting the given values:
KE = (1/2) * 3 * (7^2)
= (1/2) * 3 * 49
= (1/2) * 147
= 73.5 J
The total mechanical energy (E) is given by:
E = KE + PE
Substituting the given values:
E = 73.5 + 42
= 115.5 J
Therefore, the total mechanical energy of the object is 115.5 J.
The correct answer is C. 115.5 J.