In mechanics, acceleration is the rate of change of the velocity of an object with respect to time.
Accelerations are vector quantities (in that they have magnitude and direction). The orientation of an object's acceleration is given by the orientation of the net force acting on that object. The magnitude of an object's acceleration, as described by Newton's Second Law, is the combined effect of two causes:
the net balance of all external forces acting onto that object — magnitude is directly proportional to this net resulting force;
that object's mass, depending on the materials out of which it is made — magnitude is inversely proportional to the object's mass.The SI unit for acceleration is metre per second squared (m⋅s−2,
m
s
2
{\displaystyle {\tfrac {\operatorname {m} }{\operatorname {s} ^{2}}}}
).
For example, when a vehicle starts from a standstill (zero velocity, in an inertial frame of reference) and travels in a straight line at increasing speeds, it is accelerating in the direction of travel. If the vehicle turns, an acceleration occurs toward the new direction and changes its motion vector. The acceleration of the vehicle in its current direction of motion is called a linear (or tangential during circular motions) acceleration, the reaction to which the passengers on board experience as a force pushing them back into their seats. When changing direction, the effecting acceleration is called radial (or orthogonal during circular motions) acceleration, the reaction to which the passengers experience as a centrifugal force. If the speed of the vehicle decreases, this is an acceleration in the opposite direction and mathematically a negative, sometimes called deceleration, and passengers experience the reaction to deceleration as an inertial force pushing them forward. Such negative accelerations are often achieved by retrorocket burning in spacecraft. Both acceleration and deceleration are treated the same, they are both changes in velocity. Each of these accelerations (tangential, radial, deceleration) is felt by passengers until their relative (differential) velocity are neutralized in reference to the vehicle.
Homework Statement
A driver slows her car from 33.5 km/hr at a constant rate of 0.29 m/s2 just by taking her foot of the accelerator (the "gas" pedal). Calculate the distance the car travels during the fifth second that she is coasting.
Homework Equations
The Attempt at a Solution...
Homework Statement
A human throws a rock off of a bridge that is 30 meters above the water. It takes 3 seconds from the time the human throws the rock up in the air and falls all the way back down to the water. What is the initial velocity of the rock leaving the persons hand?Homework Equations...
Homework Statement
A marble, rolling with speed 20cm/s, rolls off the edge of a table that is 80 cm high. (a) How long does it take to drop to the floor? (b) How far, horizontally, from the table edge does the marble strike the floor?
Homework Equations
y = y0 + vy0t - (1/2)gt2...
Homework Statement
1. A train moving at a speed of 30 m/s slows down to 10m/s in 30s. How far had the train gone before it's speed was reduced from 30m/s to 20 m/s?
Homework Equations
D= Vi times T + at(squared) divide it by 2
The Attempt at a Solution
None yet. Please help me...
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Experiment 1
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