Physics 1021 Lecture Notes - Lecture 5: Microsoft Powerpoint, Projectile Motion

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ivorymarten910

22 Oct 2016

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Ball and earth attract (pull) each other. Mg=force applied by the earth on the ball. Mg=force applied by the ball on the earth b. We learnt that the falling ball accelerates downwards t(cid:449)ards earth"s (cid:272)e(cid:374)ter. This a(cid:272)(cid:272)eleratio(cid:374) is called the acceleration due to graity. There are going to be multiple choice questions that ask what forces are acting on the earth. Different planets have different accelerations due to gravity. Example: find the weight of an astronaut with mass 50kg on earth and moon. Note: the weight of the astronaut is heavier on the earth than on the moon. How to get perfect marks: action vs reaction force and questions about calculating numbers. Write the numbers that are already given to you (m and g are given to you in this example) Write down the formula (w = mg) Earth applies the gravitational force on the moon = mg. Moon applies the gravitational force on the moon =mg.

Related Questions

At a certain instant, the earth, the moon, and a stationary 1220 kgspacecraft lie at the vertices of an equilateral triangle whosesides are 3.84 \times 10^{5}\:{\rm km} in length.

Find the magnitude of the net gravitational force exerted on thespacecraft by the earth and moon.
Take the gravitational constant to be 6.673 \times 10^{-11}\:{\rmN} \cdot {\rm m}^{2}/{\rm kg}^{2}, the mass of the Earth to be 5.97\times 10^{24}\:{\rm kg}, the mass of the Moon to be 7.35 \times10^{22}\:{\rm kg}.

Find the direction of the net gravitational force exerted on thespacecraft by the earth and moon. State the direction as an anglemeasured from a line connecting the earth and the spacecraft.

What is the minimum amount of work that you would have to do tomove the spacecraft to a point far from the earth and moon? You canignore any gravitational effects due to the other planets or thesun.

Question 1

If you drop a 2.22 kg rock from a height of 1.25 m on Mars whosemass is 6.42x1023 kg and radius is 3.37x106 m, what will be the netforce on the falling rock in Newtons?Answer 8.37 N
13.4 N
19.0N
21.8 N
.

If you drop a 2.22 kg rock from a height of 1.25 m on Mars whosemass is 6.42x1023 kg and radius is 3.37x106 m, what will be therock's speed when it strikes Mars surface?Answer 1.49 m/s
2.63 m/s
3.07 m/s
5.34 m/s

What is the magnitude of the gravitational force between the Earthand the Moon? The mass of the Moon is 7.349x1022kg and its meandistance from the Earth is 3.84x108m. The equatorial radius of theEarth is 6378 km and its mass is 5.974x1024kg.Answer 1.99x1014N
1.99x1016 N
1.99x1018 N
1.99x1020 N
.

At what distance from the center of the Earth will the force ofgravity due to the Earth be Equal to the force of gravity of theMoon, i.e. where between the Earth and the Moon will the force ofgravity be the same? The mass of the Moon is 7.349x1022kg and itsmean distance from the Earth is 3.84x108m. The equatorial radius ofthe Earth is 6378 km and its mass is 5.974x1024kg.Answer 1.44x108m
1.71x108 m
2.49x108 m
3.45x108 m

(a) What is the weight of a 5.78 kg backpack at the surface ofthe Earth?
56.7 N ( I understand this problem after some time :) )
(b) What is the weight of the same backpack at the surface of theMoon where the acceleration due to gravity is only 1.6 m/s2?
9.37 N (as well as this problem)

(c) If the backpack is atthe surface of the Earth, and if a net force of 8 N is applied tothe backpack, what is the amount of acceleration of thebackpack?
(Not sure here)

m/s^2
I was thinking A = Fnet/m
Fnet being the total force on the object being equal to G(mass ofthe earth)/(radius of the earth)^2
(I know it isn't as simple as adding 8N to the weight of backpackat the surface of the earth, if I divide by the net force thatisn't adding the net force to the weight...Please Help)

(d) If the backpack is atthe surface of the Moon, and if the same net force is applied tothe backpack, what is the amount of acceleration of thebackpack?
(If I don't understand C of course I am confused on this problem aswell, thank you for your help in advance I can figure out where togo with this problem if I understand C)

m/s2
Please explain to me so that I understand for test

Physics 1021 Lecture Notes - Lecture 5: Microsoft Powerpoint, Projectile Motion

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