Superman weighs 96 kg. As usual, he is engaged in a battle to save civilization

Question

Superman weighs 96 kg. As usual, he is engaged in a battle to save civilization from an alien wishing to change the world into a reality TV program. This time the fight is in outer space. He grabs hold of the battleship, which has a mass of 1061000 kg, and pushes so hard that it goes hurtling off at a speed of 11000 m/s (relative to the reference frame in which both the hero and the battleship are initially at rest). To do this, he applies a constant force for 0.12 s before he lets go. All the action takes place in one direction, say the x direction, so we do not need to use vector notation. The battleship ends up moving in the +x direction.

Solve all problems symbolically as far as possible. If you need to first solve this problem with the numbers given, do so, and then go back and replace the numbers with symbols to obtain general symbolic expressions. Make sure that each symbolic expression has the same numerical value for the numbers given in the problem as your corresponding numerical answer.

For the numerical answers, be careful about their sign: vectors in the +x direction should be treated as positive, and vectors in the x direction treated as negative.

a) What is the acceleration of the battleship during the time Superman is pushing it? m/s^2

b) What is the force on the battleship during this time? N

c) What is the force on Superman? N

d) What is Superman's acceleration? m/s^2

e) What is Superman's final velocity? m/s

f) Now you should be able to generalize: If the final velocity of the battleship and Superman are denoted V and v respectively, and their masses are M and m respectively, obtain an expression for v in terms of the other three variables. Use ''M^2'' to denote M2 and so on.

g) g) In particular, what is MV+mv equal to? Your answer will be a number, i.e. independent of the values of the four variables. kg m/s

Explanation / Answer

a.) use equn of motion

V = u + aT

11000 = 0 + a*0.12

a = 91666.66 m/s^2

b.)F = ma

F =1061000*91666.66 = 9.725x10^10 N

c.) force on superman is also equal to force on battleship i.e = 9.725*10^10N

d.)F = ma

9.725*10^10 = 90*a

a = 1.08*10^10 m/s^2

e.) v = u+at

V = 0 +1.08*10^10*0.12

v =1.29*10^8 m/s

f.)MV = mv

v = MV/m

g.)mv+MV = 0

Related Questions

Navigate

• Browse (All)
• Browse S
• Subjects

Integrity-first tutoring: explanations and feedback only — we do not complete graded work. Learn more.