Register to reply 
Newton Open Ended Question 
Share this thread: 
#1
Jan2107, 07:40 PM

P: 9

1. The problem statement, all variables and given/known data
According to Newton's Law of Universal Gravitation, the force exerted by the earth on an object is directly proportional to the objects mass According to Newton's Second Law of Motion, the acceleration of an object is directly proportional to the force being exerted on it. Therefore, it may be concluded that if 2 objects are dropped simultaneously from the same height, the heavier object, having a greater acceleration, will reach the ground first. Using mathematical equations, verify or refute the above conclusion 2. Relevant equations 3. The attempt at a solution I have a strong feeling the statement needs to be refuted, just not sure what equations to use in the process, besides F=MA for Newton's Second Law 


#2
Jan2107, 08:18 PM

Emeritus
Sci Advisor
PF Gold
P: 4,980

When you drop two object what force accelerates them?



#3
Jan2107, 08:58 PM

P: 9

Gravity, right? but im just unsure of whether more mass constitutes greater acceleration...



#4
Jan2107, 09:08 PM

Mentor
P: 8,325

Newton Open Ended Question
Do you know how to calculate the gravitational force between two objects?



#5
Jan2107, 09:24 PM

P: 9

multiply the 2 masses, then divide by the distance squared



#6
Jan2107, 09:27 PM

P: 9

ooh so the mass of the objects would not affect their acceleration, and therefore they would reach the ground at the saem height, correct?... but that doesn't seem right to me, since a feather would take longer than a bowling ball, or does that have to do w/ weight?



#7
Jan2107, 09:28 PM

Mentor
P: 8,325

Close; you need the gravitational constant. So, the force of gravity exerted by the earth (mass M) on an object (mass m) at a distance r is [tex]F=\frac{GMm}{r^2}[/tex] Now, use this in Newton's second law.



#8
Jan2107, 09:35 PM

P: 9

So, 2 objects dropped at the same time would hit the ground at the same time, since the force being exerted on the objects is the same.



#9
Jan2107, 09:35 PM

Emeritus
Sci Advisor
PF Gold
P: 4,980

A rather famous experiment was done on the moon where an Apollo astronaut dropped a feather and hammer at the same time. Of course the moon has no atmosphere. Check out the vid below: http://www.youtube.com/watch?v=5C5_dOEyAfk 


#10
Jan2107, 09:38 PM

P: 344

You don't have to use newtons law of gravity unless you want to find out how fast the 2 objects are accelerating towards earth or some other object. Keep it simple with
F=ma On the surface of the earth things accelerate at 9.8 m/s or 32.2 f/s (assuming no air resistance) so input that. F=m*9.8m/s M= mass so the mass can be 1 gram or it could be a kilogram if you like. No matter what the mass is, it isn't going to change the acceleration (9.8 m/s) of an object. The only thing mass changes is the force. 


#11
Jan2107, 09:39 PM

Mentor
P: 8,325




#12
Jan2107, 09:44 PM

P: 9

alright im going to bed in 5 minutes and this is due tommrow: so, they will arrive at the same time bc they are both affected by the gravitational constant?



#13
Jan2107, 09:44 PM

P: 9

oh sweet thank you all for the help



#14
Jan2107, 09:47 PM

Sci Advisor
HW Helper
PF Gold
P: 6,047




#15
Jan2107, 09:52 PM

P: 344




#16
Jan2107, 09:59 PM

Sci Advisor
HW Helper
PF Gold
P: 6,047




#17
Jan2107, 10:01 PM

Emeritus
Sci Advisor
PF Gold
P: 4,980

The acceleration on both objects is the same but the forces are different for each one and the force is due to gravity. 


#18
Jan2107, 10:10 PM

P: 344

Am i missing something?? 


Register to reply 
Related Discussions  
Open ended pipe Harmonics Mastering Physics Question  Introductory Physics Homework  9  
Newton`s 3rd Law Tension Solved Question  Introductory Physics Homework  7  
Re: Philosophia experimentalis before Newton  General Physics  0  
Why does an open ended column reflect sound?  General Physics  5  
An open ended ODE problem  Differential Equations  5 