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CollegeStudent
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Homework Statement
An asteroid (space rock) is 10 m in width and has a density of an average Earth rock of 2000 kg/m^3 (2.0 g/cm^3). (a) Find the mass of the asteroid? (b) Suppose (unrealistically) that the asteroid starts from rest half way between the Moon and the Earth (6.0 x 10^5 km) and accelerates toward the Earth at and average acceleration of (1/10) g = 1.0 m/s^2. What will the velocity of the asteroid be when it reaches the Earth. Note: although the assumptions are unrealistic the result will agree with what is known about asteroid velocities as they pass the Earth. (c) Now calculate the kinetic energy of this asteroid when it reaches Earth. Convert this to tons of TNT (1.0 ton TNT = 1.0 tn = 4.186 x 10^9 J). For comparison purposes note that the atomic (fission) bomb dropped on Hiroshima was about 12 - 14 ktn (kilotons TNT). (d) Finally, how much kinetic energy would an asteroid ten times wider or 100 m wide (still only a medium size asteroid) under the same conditions bring to Earth upon impact?
Homework Equations
The Attempt at a Solution
(a) Find the mass of the asteroid?
I was thinking of using the ol' D = M/V formula...but I have no way of finding V
(b) I have no idea what to do here...I was thinking using graviational potential energy = mgh being converted to kinetic energy 1/2mv²...but I'm not sure...and still can't figure it out without the mass
(c) Now calculate the kinetic energy of this asteroid when it reaches Earth
I thought I would use the results of V (from part (b)) and M (from part (a)) and find K.E here...but the fact that it says "when it reaches Earth" throws me off and makes me think otherwise
any help here? Thanks in advance