Question

Physics A Level Question, Please help. :/
Parts i and ii.

Answer 1

@aaronq @Abhisar

Answer 2

please note that, potential energy of your object ii the earth gravitational field, is:
\[U(d)=\frac{ GMm }{ d+R }\]
where M is mass of earth, m is mass of your object, d is the altitude of your object with respect to earth surface, and R is earth radius

Answer 3

oops.. G is the Gravitational constant

Answer 4

of course, when your object is at earth surface, its potential energy is:
\[U(R)=G \frac{ Mm }{ R }\]

Answer 5

so the change in potential energy, is:
\[U(R)-U(d+R)=G \frac{ Mm }{ R }-G \frac{ Mm }{ d+R}=...\]

Answer 6

please insert your numerical data @MonsterIsEnergy

Answer 7

Oh thank you so much !
But what do you mean by U(d) and U(R) ?
I get the rest of it though ^-^
I appreciate it thanks!

Answer 8

Oh wait

Answer 9

I get it now!

Answer 10

U(d) is the potential energy of your object at its final position, whereas U(R) is potential energy of your object at its initial position, namely before to be launched

Answer 11

Aha I see, but in the question, how do we use the altitude, ....

Answer 12

the altitude is d

Answer 13

All righty thank you so much ^-^
Have a great day

Answer 14

please, do you know how to calculate the speed of your object, at launch

Answer 15

Using the kinetic energy formula?

Answer 16

0.5 m v^2 = m X change in potential

Answer 17

please note that in the earth gravitational field the total energy has to be remain constant, namely
\[\frac{ GMm }{ R}=+\frac{ 1 }{ 2 }mV ^{2}=G \frac{ Mm }{ d+R }+\frac{ 1 }{ 2 }m V _{f}^{2}\]
where V_f is the speed of your object at its final position. I think that V_f=0, do you agree?

Answer 18

oops sorry:
\[G \frac{ Mm }{ R }+\frac{ 1 }{ 2 }mV ^{2}=G \frac{ Mm }{ d+R }+\frac{ 1 }{ 2 }mV _{f}^{2}\]

Answer 19

and V is the speed of your object at initial position, namely the launch speed

Answer 20

Ohhhh yep that makes a lot of sense I will go over all of that once more , thanks.

Answer 21

thanks!!

Answer 22

Thank YOU ^-^

Answer 23

Thank YOU!!

Answer 24

Awh nope haha, thank YEW! xD lol.