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

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Answer 1 · 2017-10-26T19:40:49

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

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