toesockshoe said:For example, when you are on a rollercoaster and you go past the tip of the coaster you feel like you are going to fly off your seat... however you are radially accelerating down. Same thing when you take a u-turn in a car. you are radially accelerating to your left (atleast in america) however you feel like you are being pushed to your right.
Why is this?
well what I'm asking is why do we feel like we're going against acceleration? When we are at the top of the rollercoaster the net force is downward... I would expect that we would feel a downward jerk because we are accelerating downward. Why is it the opposite?ZapperZ said:Just to clarify, you are really asking why Newton's First Law is valid, aren't you?
Zz.
toesockshoe said:well what I'm asking is why do we feel like we're going against acceleration? When we are at the top of the rollercoaster the net force is downward... I would expect that we would feel a downward jerk because we are accelerating downward. Why is it the opposite?
It would accelerate to the center of the string (the point of rotation).ZapperZ said:I think you got this all wrong.
If you tie a ball to a string, and then spin it round in a circle, what is the direction of the force? And what is the direction of the acceleration?
Now, if you are the ball (i.e. I attach you to a string and then spin you around in a circle), what forces do you feel that are acting on you? In this case, does the fact that you are in a non-inertial reference frame has any bearing to what you THINK are the forces that you experience?
In both cases, try to draw a free-body diagram of the forces. Now use this and see if you can reformulate your question, and whether my re-interpretation of your question makes any sense.
Zz.
Because our observed motion (measured against the roller coaster cart or against the interior of your automobile) does not match the felt force from the cart or car. We see ourselves stationary with respect to the cart or car. We physically feel a lowered supporting force (for the cart at the top of its arc) or a leftward push (for a leftward turning car). But we account for the discrepancy between felt force and observed lack of movement by imagining the presence of an additional "inertial" force directed opposite to the true acceleration.toesockshoe said:well what I'm asking is why do we feel like we're going against acceleration?
jbriggs444 said:Because our observed motion (measured against the roller coaster cart or against the interior of your automobile) does not match the felt force from the cart or car. We see ourselves stationary with respect to the cart or car. We physically feel a lowered supporting force (for the cart at the top of its arc) or a leftward push (for a leftward turning car). But we account for the discrepancy between felt force and observed lack of movement by imagining the presence of an additional "inertial" force directed opposite to the true acceleration.
We imagine that it is this inertial force that is lifting us off of the roller coaster seat or pushing us rightward against the passenger side door.
The key concern is that the "a" in f=ma depends on your choice of coordinate system.toesockshoe said:Ahh, ok. that makes sense. So what is it about inertial foces that makes it hard to do F=ma? My prof said that those forces (im assuming inertial forces are the same as pseudo forces) makes solving F=ma problems confusing.
toesockshoe said:I was told that you can not do F=ma in a non inertial frame, so how can I answer the 2nd question if I AM the ball? Wouldn't I be accelerating meaning I can't do F=ma.
toesockshoe said:well what I'm asking is why do we feel like we're going against acceleration? When we are at the top of the rollercoaster the net force is downward... I would expect that we would feel a downward jerk because we are accelerating downward. Why is it the opposite?
toesockshoe said:For example, when you are on a rollercoaster and you go past the tip of the coaster you feel like you are going to fly off your seat...
in the thread you just posted... in comment number 10 you saidA.T. said:Here is an old thread about what you feel on a roller coaster:
https://www.physicsforums.com/threads/a-questiona-about-equivalence-principle.794359/#post-4989434
... wouldn't the acceleration actually be 9.8 (considering the coaster is perfectly vertical)? why is it 0?terrible all the time because your proper acceleration is constant at zero
Proper acceleration is what an accelerometer measures, which is zero in free fall.toesockshoe said:in the thread you just posted... in comment number 10 you said ... wouldn't the acceleration actually be 9.8 (considering the coaster is perfectly vertical)? why is it 0?
Objects resist changes in motion because of inertia, which is the tendency of an object to maintain its state of motion. This means that an object will remain at rest or continue moving at a constant velocity unless acted upon by an external force.
The relationship between mass and acceleration is described by Newton's second law of motion, which states that the acceleration of an object is directly proportional to the net force acting on it and inversely proportional to its mass. This means that an object with a larger mass will require a greater force to accelerate it compared to an object with a smaller mass.
Friction is a force that opposes motion and it can decrease the acceleration of an object. This is because friction acts in the opposite direction of the motion, resulting in a decrease in the net force acting on the object and thus a decrease in its acceleration.
Yes, an object can have zero acceleration if the net force acting on it is zero. This can happen if the object is at rest or if it is moving at a constant velocity.
In real-life situations, it is difficult to achieve constant acceleration because of external factors such as air resistance, friction, and other forces that may act on the object. These factors can cause variations in the acceleration of an object and make it difficult to maintain a constant acceleration.