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Why is the direction of free-fall acceleration usually negative?
Wiki User
∙ 12y ago
Free fall is defined as ''the motion of an object undergoing an acceleration of g'' As we know acceleration is a vector quantity and 'g' acts vertically downwards. Also, the only force acting on an object in free fall is its weight and weights acts downwards.
Wiki User
∙ 12y ago
Wiki User
∙ 15y agoFree fall's association with gravity is probably why free fall acceleration is negative.
For example dropping a ball is called positive energy by Physicists, when the force of gravity is downward and the ball moves downward.
Physicists like Maxwell considered the free fall energy positive. Physicists like Hamilton said the energy is negative. Maxwell was using Hamilton's vectors which have the rule ii=-1, thus the negative sign when the gravity force was (if) and the displacement was (id) so (if) (id)=ii fd=-fd. The minus sign indicates that the work is output, exergy; free fall gives work out, exergy, not energy (work in).
Maxwell and most all physicists insisted that a ball falling down was positive energy. To fix this problem, J Willard Gibbs created a new Vector Mathematics that made ii=+1 and that is the vector mathematics rule used today in physics and it is wrong mathematically and physics wise but it is the rule today so that a ball falling down has positive energy.
Quaternions is the proper mathematics to be used in physics.
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What is deceleration in physics?
'Acceleration' is defined as the rate of change in velocity and the direction of the change. 'Deceleration' is a popular but unscientific word used to describe acceleration with a negative magnitude, i.e. 'slowing down' without regard for its direction.
How is a negative acceleration different from a positive acceleration?
Actually, it depends on how you define the coordinate axes, but usually when moving forward, negative acceleration decreasesspeed, positive acceleration increasesit.
When is acceleration due to gravity positive and when is it negative?
Acceleration due to gravity is negative when an object is moving up. Accl'n due to gravity is positive when an object is moving down (since gravity acts downwards on an object). ^Acceleration due to gravity is always negative, while the acceleration of the ball upward was positive due to what threw it, not gravity.
How does speed and velocity affect basketball?
Acceleration changes the speed - usually increases it. A reduction is speed is negative acceleration , or deceleration. Acceleration can change the speed or direction (or both) of velocity.
Why there is no acceleration along x axis during projectile motion?
There is no force that acts upon the object in that direction. Gravity only acts on the y axis. Though there is some wind resistance that does cause a negative acceleration in the x direction. You are probably just being told to ignore this as it is usually negligible.
Can there be a positive acceleration and a negative acceleration?
Yes, acceleration can be positive and negative because acceleration is a vector. It has both direction and magnitude. The direction is what makes it positive or negative. Negative acceleration is usually called deceleration.
When is acceleration neg?
Acceleration is negative if velocity is decreasing with time. Since velocity is a vector this can occur in one of two ways: 1) you are slowing down in the direction of motion and the velocity in that direction is defined as positive (this is what we usually mean by negative acceleration) 2) you are speeding up in the direction of motion and the velocity in that direction is defined as negative. An example of this is an object launched into the air which immediately starts to decelerate in it's upward velocity, reaches it's highest velocity, and then begins accelerating towards the ground. If we call the velocity upward a positive velocity, then when it starts falling, it has negative velocity. Note that acceleration (due to gravity) is negative the whole time.
What is deceleration in physics?
'Acceleration' is defined as the rate of change in velocity and the direction of the change. 'Deceleration' is a popular but unscientific word used to describe acceleration with a negative magnitude, i.e. 'slowing down' without regard for its direction.
How is a negative acceleration different from a positive acceleration?
Actually, it depends on how you define the coordinate axes, but usually when moving forward, negative acceleration decreasesspeed, positive acceleration increasesit.
When is acceleration due to gravity positive and when is it negative?
Acceleration due to gravity is negative when an object is moving up. Accl'n due to gravity is positive when an object is moving down (since gravity acts downwards on an object). ^Acceleration due to gravity is always negative, while the acceleration of the ball upward was positive due to what threw it, not gravity.
How does speed and velocity affect basketball?
Acceleration changes the speed - usually increases it. A reduction is speed is negative acceleration , or deceleration. Acceleration can change the speed or direction (or both) of velocity.
Why there is no acceleration along x axis during projectile motion?
There is no force that acts upon the object in that direction. Gravity only acts on the y axis. Though there is some wind resistance that does cause a negative acceleration in the x direction. You are probably just being told to ignore this as it is usually negligible.
Can your net force and acceleration be in opposite directions?
No, they are always in the same direction, as expressed in Newton's Second Law, which is usually expressed as: F=ma (force = mass x acceleration). In this equation, acceleration is a vector, so when multiplying it by a mass (which is NOT a vector), you get another vector that points in the same direction.
What is on the x axis and y axis on both a speed and acceleration graph?
Conventionally, the x axis is time and usually the y axis is, respectively, radial speed and radial acceleration. In such examples, the y-variables are measured in one direction from a fixed point (the origin). Motion across that direction is usually ignored.
Is stems growing upward positive or negative?
An upward direction is usually considered positive.
What is the significance of negative values on projectiles?
None, really. A projective is usually an object that is incapable of self-propulsion, and which is launched by an initial force. From that point on, it is acted upon by gravity (and if you are more advanced, by air resistance). Because of these forces, an object that is launched in an upward-sloping direction eventually starts moving downwards. The decision to call the upward direction the positive (initial motion is positive but acceleration is negative) or as negative (initial motion is negative but acceleration is positive) is purely arbitrary. Moreover, there are not even conventions on this matter because there are cases where one or the other option has minor arithmetical advantages. No significance can be attached to something that is based on an arbitrary decision.
Rate of change of the velocity of an object?
The change in velocity is just the change in velocity. The RATE of change of velocity - how quickly velocity changes - is usually called "acceleration".
