GPE is the gravitational Potential Energy which is given by mgh.
mg is the gravitational force(a force) and h is the height of the object(or distance of the object from earth's surface)
SO GPE = mg (force) x h (distance)
Explanation:
To show - from E=mc²=hv show that wavelength=h/mv
Proof -
Given that,
E = mc²
E = hν
By equating both the equations, we get
mc² = hν
Because real particles do not travel at the speed of light, De Broglie submitted velocity ( v ) for the speed of light ( c ).
mv² = hν
Through the equation λ , de Broglie substituted v/λ for ν and arrived at the final expression that relates wavelength and particle with speed.
mv² = hv/λ
⇒λ = hv/mv²
⇒λ = h/mv
Hence showed.
Negative force
The woman is applying force to stop the child or to prevent him from running.
I hope this helps...
I would say you should use or test it once a week to ensure it is working properly in an active laboratory since it is a workplace with significant chemical hazards so it would give peace of mind to know on a quite regular basis that it can be relied on in case of an emergency like an eye flush for example.
