Question

Gabriel is performing an experiment in which he is measuring the energy and work being done by a ball rolling down a hill. Which statement best describes Gabriel's measurements?

Answer 1

Answer:

They will both be recorded in Joules

Explanation:

- The energy of an object refers in general to the mechanical energy of the object, which is the sum of its kinetic energy (KE), which is the energy of motion, and of its potential energy (PE), which is the energy due to its position above the ground:

$E=PE+KE$

- The work done by an object is equal to the product between the force exerted by the object, F, and the displacement, d:

$W=Fd$ (1)

The SI units of the energy is the Joules, J. The basic equivalence with SI units can be seen from the definition of kinetic energy:

$KE=\frac{1}{2}mv^2$

where

m is the mass, measured in kilograms (kg)

v is the speed, measured in meters per second (m/s)

So we have, since the speed is squared

$1 J = 1 kg\cdot \frac{m^2}{s^2}$

Now we can check from eq.(1) that the work as the same units. In fact, the force is measured in Newtons (N), and we know that force is equal to mass times acceleration, so we have:

$1 N = 1 kg \cdot \frac{m}{s^2}$

Distance is measured in meters (m), so the work is measured in

$[W]=[kg \cdot \frac{m}{s^2}][m]=[kg\cdot \frac{m^2}{s^2}]$

Which corresponds to the definition of Joule. Therefore, both energy and work are measured in Joules.

Answer 2

Answer:

B

Explanation: