Question

We need to find the energy equivalent and the speed. Can I get some help please? Thanks!

Answer 1

A) `E = 4.5*10^17 J`
B) `v = 120 m/s`#

Explanation:

A) This calls for Einstein's famous formula
`E = m*c^2`

Plugging in the data,

`E = 5 kg*(3*10^8 m/s)^2 = 5 kg * 9*10^16 m^2/s^2`

So `E = 45*10^16 kg*m^2/s^2 = 4.5*10^17 kg*m^2/s^2`

We want units that indicate energy, so group the units we have so that you can see force*distance (which is how you calculate work).

`E = 4.5*10^17 (kg*m/s^2)*m = 4.5*10^17 J`

B) Use the suvat formula
`v = u + a*t`

Without air resistance, the acceleration = `g = 9.8 m/s^2`.
`v = 0 + 9.8 m/s^2*12 s = 117.6 m/s`,
`"or, with 2 significant digits", 120 m/s.`

I hope this helps,
Steve