物理題目(2題)

1.設地球半徑為6400KM,地面的g=9.8m/s^2,則離地面300KM的g為多少?

Ans:

By the Newton's law , we know that mg = GMm/R^2

so g is proportional to the inverse of R^2

such that g'/g=R^2/R'^2

=> g'/9.8=(6400^2 km^2)/((6400+300)^2 km^2)

=> g'=8.94 Nkg^-1//

2.質點A(質量m)具有+X方向的速度V,與另一靜止的質點B(質量M)相撞後,質點A的速度為何?

By the conservation of momentum ,




2009-04-12 12:48:26 補充：
i can't understand the meaning of second question

For question 2, there is insufficient information. Neither the coefficient of restitution nor the final velocity of one of the object is given.