Question

If A 700 kg car is driving on a bridgeIt has 50, 000J of mechanical energy and 30,000 of kinetic energy, how high is the bridge?

Answer 1

Answer:

2.92 m

Explanation:

The mechanical energy is equal to the sum of kinetic energy and potential energy.

Since PE = mgh where m is the mass, g is the gravity and h is the height, we get:

$\begin{gathered} PE+KE=ME \\ mgh+KE=ME \end{gathered}$

Now, we can solve the equation for h, so

$\begin{gathered} \text{mgh}=ME-KE \\ h=\frac{ME-KE}{mg} \end{gathered}$

Then, replacing ME = 50,000J, KE = 30,000 J, m = 700 kg and g = 9.8 m/s, we get:

$h=\frac{50000-30000}{700(9.8)}=2.92\text{ m}$

Therefore, the height of the bridge is 2.92 m