Question

1. What is the kinetic energy of a 65 kg rocket traveling at 109 m/s? ( ____ J )

Type answer as a whole number (no decimals). Type the number only, not the units. Use commas: for example, type 100,000, not 100000




2. What is the momentum of the rocket in the previous problem? ( _____ kg · m/s)
Type answer as a whole number (no decimals, no commas). Type the number only, not the units.

Answer 1

1) The kinetic energy of an object is equal to

`K= (1)/(2)mv^2`
where
m is the object mass
v its velocity

For the rocket in our problem, the mass is m=65 kg and the velocity is v=109 m/s, so its kinetic energy is

`K= (1)/(2)(65 kg)(109 m/s)^2=386133 J = 3.86 \cdot 10^5 J`

2) The momentum of the rocket is given by

`p=mv`
where m is the rocket mass and v its velocity. Substituting again the data of the rocket, we find:

`p=(65 kg)(109 m/s)=7085 kg m/s=7.09 \cdot 10^3 kg m/s`