TheMadHatteress
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Hi. So, I'm really really bad at Physics, always have been because I have problems in my basic understanding of the subject. So the following are some really basic questions which I'm too embarrassed to ask my teacher and have avoided asking them for so long:
1. why are both acceleration due to gravity and gravitational field strength referred to as 'g'?
2. why is the acceleration due to gravity the same for objects of different masses when there is no air resistance?
3.why, oh why, do objects actually accelerate when they fall towards the earth?
4. why is the acceleration when going up negative?
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Chlorophile
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(Original post by TheMadHatteress)
Hi. So, I'm really really bad at Physics, always have been because I have problems in my basic understanding of the subject. So the following are some really basic questions which I'm too embarrassed to ask my teacher and have avoided asking them for so long:
1. why are both acceleration due to gravity and gravitational field strength referred to as 'g'?
2. why is the acceleration due to gravity the same for objects of different masses when there is no air resistance?
3.why, oh why, do objects actually accelerate when they fall towards the earth?
4. why is the acceleration when going up negative?
1. They're both referred to as g because they're the exact same thing. The gravitational field strength is defined as the force per unit mass acting on an object at a particular point in space, which is also the exact same thing as saying the acceleration due to gravity. It's probably important to mention that g is specific to points, not objects. The value of g that we use on earth, 9.81N/Kg, is not a property of the earth, it's simply the force we experience at ground level, mainly due to the impact of the earth. If you're higher up in space, the value of g is lower.
2. The gravitational field strength is a force per unit mass, i.e N/Kg. So the greater the mass of an object, the greater the force on it due to gravity. However, acceleration is given by F=ma, or a=F/m. Therefore, as the mass of an object increases, the force required to create a given acceleration also increases. If you do the maths, the masses cancel out and the effect of gravity is a constant acceleration for all objects (in a given point of space).
3. Since a=F/m, whenever there is a resultant force F, there will be acceleration. If you drop an object from stationary, the force induced by gravity will initially be greater than any resistive forces so there is therefore a resultant force, and hence an acceleration.
4. Acceleration is a vector, which means that it takes into account direction. The important thing is that acceleration in one direction is positive, and acceleration in the other direction is negative. Acceleration going up is only negative if we define acceleration going down to be positive.
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TheMadHatteress
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(Original post by Chlorophile)
1. They're both referred to as g because they're the exact same thing. The gravitational field strength is defined as the force per unit mass acting on an object at a particular point in space, which is also the exact same thing as saying the acceleration due to gravity. It's probably important to mention that g is specific to points, not objects. The value of g that we use on earth, 9.81N/Kg, is not a property of the earth, it's simply the force we experience at ground level, mainly due to the impact of the earth. If you're higher up in space, the value of g is lower.
2. The gravitational field strength is a force per unit mass, i.e N/Kg. So the greater the mass of an object, the greater the force on it due to gravity. However, acceleration is given by F=ma, or a=F/m. Therefore, as the mass of an object increases, the force required to create a given acceleration also increases. If you do the maths, the masses cancel out and the effect of gravity is a constant acceleration for all objects (in a given point of space).
3. Since a=F/m, whenever there is a resultant force F, there will be acceleration. If you drop an object from stationary, the force induced by gravity will initially be greater than any resistive forces so there is therefore a resultant force, and hence an acceleration.
4. Acceleration is a vector, which means that it takes into account direction. The important thing is that acceleration in one direction is positive, and acceleration in the other direction is negative. Acceleration going up is only negative if we define acceleration going down to be positive.
Thank you so much!
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