Question

An model leans off a bridge railing to take a picture and accidentally drops their phone. The phone's mass is 0.115 kg and the bridge is 15 m tall. The instant the model dropped the phone, it's mechanical energy is 16.9 joules? why?

Answer 1

The statement is true:

Step-by-step explanation:

As said in the statement, we need to measure the mechanical energy(M.E) of the phone at the instant is dropped:

M.E = P.E + K.E

Given the fall hasn't yet begun, the kinetic energy (K.E) is equal to zero so M.E = P.E

We must use the Potential Energy formula :

P.E = h x m x g

We know that g is equal to 9.8
`J.kg^(-1) .m^(-1)` on Earth, the height is 15m and m is 0.115:

M.E = 15 x 0.115 x 9.8 = 16.9 Joules