Reflecting on Energy Calculation in Physics
What is the energy required to bench press 110 kg a distance of 0.7 meters?
a) The energy required is 76.65 J, and the barbell has gravitational potential energy.
b) The energy required is 76.65 J, and the barbell has kinetic energy.
c) The energy required is 764.5 J, and the barbell has kinetic energy.
d) The energy required is 754.6 J, and the barbell has gravitational potential energy.
Answer:
The energy required to bench press 110 kg a distance of 0.7 meters is calculated to be 754.6 Joules. The barbell has gravitational potential energy when it is at rest at the top of this height. Hence, the correct option is d) The energy required is 754.6 J, and the barbell has gravitational potential energy.
Explanation:
The energy required to bench press 110 kg a distance of 0.7 meters can be calculated using the formula for work, which is equal to force times distance. In this case, the force is the weight of the barbell, which can be calculated as mass times gravity. The gravity here on earth is approximately 9.8 m/s². So the force comes out to be 110 kg * 9.8 m/s² = 1078 Newtons. Multiplying this force by the distance (0.7 meters) we get: 1078 N * 0.7 m = 754.6 Joules. This is the energy required to lift the barbell to that height. As for the type of energy the barbell has while at rest at the top, it has potential energy. More specifically, it has gravitational potential energy, which can be described as the energy an object possesses because of its position in a gravitational field.
Therefore, the correct answer is: d) The energy required is 754.6 J, and the barbell has gravitational potential energy.