Primarygun Posted November 21, 2004 Share Posted November 21, 2004 1.Which newton's law describes inertia is proportional to mass? 1st or 2nd? 2.An object is on a slope, the graph of v-t shows that there is negative acceleration, how do you explain it ? Link to comment Share on other sites More sharing options...
Primarygun Posted November 21, 2004 Author Share Posted November 21, 2004 1.Which newton's law describes inertia is proportional to mass? 1st or 2nd? 2.An object is on a slope, the graph of v-t shows that there is negative acceleration, how do you explain it ? Link to comment Share on other sites More sharing options...
fuhrerkeebs Posted November 21, 2004 Share Posted November 21, 2004 1. 2nd. F=ma is formulated by saying that a=kF/m, and in SI units k is set to 1. 2. The object is going up the slope, not down. Link to comment Share on other sites More sharing options...
fuhrerkeebs Posted November 21, 2004 Share Posted November 21, 2004 1. 2nd. F=ma is formulated by saying that a=kF/m, and in SI units k is set to 1. 2. The object is going up the slope, not down. Link to comment Share on other sites More sharing options...
bloodhound Posted November 21, 2004 Share Posted November 21, 2004 i thought it was the first that describes intertia proportional to mass you can't really call it negative acceleration. it all depends on the way you choose your unit vectors. for example in a problem invovling dropping a stone from a cliff, and finding the distance it travels in time t, it would be more convinient for me to choose the 3rd unit vector pointing down. giving me a positive acceleration. i could choose the 3rd unit vector pointing upwards, that will give me the same result as well. Link to comment Share on other sites More sharing options...
bloodhound Posted November 21, 2004 Share Posted November 21, 2004 i thought it was the first that describes intertia proportional to mass you can't really call it negative acceleration. it all depends on the way you choose your unit vectors. for example in a problem invovling dropping a stone from a cliff, and finding the distance it travels in time t, it would be more convinient for me to choose the 3rd unit vector pointing down. giving me a positive acceleration. i could choose the 3rd unit vector pointing upwards, that will give me the same result as well. Link to comment Share on other sites More sharing options...
mak10 Posted November 21, 2004 Share Posted November 21, 2004 1.Which newton's law describes inertia is proportional to mass? 1st or 2nd? i think its the first law since it describes how objects continue with their state of rest or motion unless compelled otherwise by an external force. the bigger the mass, the more inertia requied to affect its state. the second law highlights only the rate of change of momentum of a body in the direction of the force. 2.An object is on a slope, the graph of v-t shows that there is negative acceleration, how do you explain it ? the object is decelerating. -mak10 Link to comment Share on other sites More sharing options...
mak10 Posted November 21, 2004 Share Posted November 21, 2004 1.Which newton's law describes inertia is proportional to mass? 1st or 2nd? i think its the first law since it describes how objects continue with their state of rest or motion unless compelled otherwise by an external force. the bigger the mass, the more inertia requied to affect its state. the second law highlights only the rate of change of momentum of a body in the direction of the force. 2.An object is on a slope, the graph of v-t shows that there is negative acceleration, how do you explain it ? the object is decelerating. -mak10 Link to comment Share on other sites More sharing options...
Primarygun Posted November 21, 2004 Author Share Posted November 21, 2004 Actually, the 2nd question is very silly asked by me. LOL. Inertia always accompany 1 st in textbooks. However,I think it is the 2nd law. Link to comment Share on other sites More sharing options...
Primarygun Posted November 21, 2004 Author Share Posted November 21, 2004 Actually, the 2nd question is very silly asked by me. LOL. Inertia always accompany 1 st in textbooks. However,I think it is the 2nd law. Link to comment Share on other sites More sharing options...
ecoli Posted December 3, 2004 Share Posted December 3, 2004 Fnet = m/a The net force thats is acting upon an object is directly proportionaa to the mass of the object, and indirectly proportional to the acceleration of an object. Link to comment Share on other sites More sharing options...
bloodhound Posted December 4, 2004 Share Posted December 4, 2004 i swear to god, it should be first. i dont see what the second law has to do with inertia this is the meaning of inertia from the oxford online dictionary (physics) a property (= characteristic) of matter (= a substance) by which it stays still or, if moving, continues moving in a straight line unless it is acted on by a force outside itself. Link to comment Share on other sites More sharing options...
swansont Posted December 4, 2004 Share Posted December 4, 2004 You can't really answer the question if you don't actually know what Newton's laws are. The first law doesn't mention mass at all: An object at rest remains at rest, and an object in (uniform) motion remains in (uniform) motion unless acted upon by a net external force. Link to comment Share on other sites More sharing options...
bloodhound Posted December 4, 2004 Share Posted December 4, 2004 well that IS the meaning of inertia... and by object, Newton's obviously means mass. what else can he mean? Link to comment Share on other sites More sharing options...
swansont Posted December 4, 2004 Share Posted December 4, 2004 The first law certainly describes the concept or principle of inertia, but it's in the second law that the term is quantified as being mass. edit to add: the first law also tells you when you can apply Newton's laws. If and object at rest does not remain at rest, etc., you are not in an inertial frame of reference. Link to comment Share on other sites More sharing options...
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