In physics and mathematics, the dimension of a mathematical space (or object) is informally defined as the minimum number of coordinates needed to specify any point within it. Thus a line has a dimension of one (1D) because only one coordinate is needed to specify a point on it – for example, the point at 5 on a number line. A surface such as a plane or the surface of a cylinder or sphere has a dimension of two (2D) because two coordinates are needed to specify a point on it – for example, both a latitude and longitude are required to locate a point on the surface of a sphere. The inside of a cube, a cylinder or a sphere is three-dimensional (3D) because three coordinates are needed to locate a point within these spaces.
In classical mechanics, space and time are different categories and refer to absolute space and time. That conception of the world is a four-dimensional space but not the one that was found necessary to describe electromagnetism. The four dimensions (4D) of spacetime consist of events that are not absolutely defined spatially and temporally, but rather are known relative to the motion of an observer. Minkowski space first approximates the universe without gravity; the pseudo-Riemannian manifolds of general relativity describe spacetime with matter and gravity. 10 dimensions are used to describe superstring theory (6D hyperspace + 4D), 11 dimensions can describe supergravity and M-theory (7D hyperspace + 4D), and the state-space of quantum mechanics is an infinite-dimensional function space.
The concept of dimension is not restricted to physical objects. High-dimensional spaces frequently occur in mathematics and the sciences. They may be parameter spaces or configuration spaces such as in Lagrangian or Hamiltonian mechanics; these are abstract spaces, independent of the physical space we live in.
Homework Statement
I am solving a kinematic problem, where I have a link that is attached to a rotational joint. I need to find the position of the joint for t=0..8, and I need to do it for every 0.01s. The problem comes from the fact that I have three stages for the velocity, during t = 0..0.1...
Homework Statement
A car traveling at a constant speed of 24.0m/s passes a trooper hidden behind a billboard. One second after the speeding car passes the billboard, the trooper sets off in a chase with a constant acceleration of 3.0m/s^2.
A) How long does it take the trooper to overtake the...
Homework Statement
A locomotive has a mass of 40 tonnes.
In one situation, the locomotive is pulling two trucks, each of mass 10 tonnes
Calculate the tension in the coupling pulling the two trucks behind the locomotive.
The coupling is positioned such that it is linking the locomotive and the...
Consider the 1d motion of a body under the influence of the force given by F = -m*γ*vα. m is mass, γ is a constant of appropriate dimension, v is velocity and α is dimensionless constant. The value of α for which the motion will come to a stop in finite time is to be calculated. I solved the...
Homework Statement
Two railroad tracks intersect at right angles at station O. At 10AM the train A, moving west with constant speed of 50 km/h, leaves the station O. One hour later train B, moving south with the constant speed of 60 km/h, passes through the station O. Find minimum distance...
<<Moderator note: LaTeX corrected>>
Problem:
> Two cars A and B move with velocity ##60 kmh^{-1}## and ##70 kmh^{-1}##. After a certain time, the two cars are 2.5 km apart. At that time, car B starts decelerating at the rate 20 kmh-2. How long does Car A take to catch up with Car B?
I tried to...
Homework Statement
A rock is released from rest from the top of a very high cliff, and accelerates downward at g.
Approximately how far does the rock travel in the first 7 seconds of its free-fall? (Assume no air friction.)
Homework Equations
X=Xo+VoT+1/2AT^2
The Attempt at a Solution
I...
A classical particle constrained to move in one dimension (x) is in the potential field V(x) = V0(x – a)(x –b)/(x – c)^2, 0 < a < b < c < ∞.
a. Make a sketch of V
b. Discuss the possible motions, forbidden domains, and turning points. Specifically, if the
particle...
Homework Statement
Pelicans tuck their wings and free-fall straight down when diving for fish. Suppose a pelican starts its dive from a height of 18.0m and cannot change its path once committed. If it takes a fish 0.25s to perform evasive action, at what minimum height must it spot the pelican...
1. A uniformly retarded moving motorcycle covers 250 meters in the first 10 seconds and and 250 meters in the next 20 seconds.How much will it travel more to come before coming to a halt?
250 = 10u - 50a , 250 = 20u - 200a. On solving these i get and a retardation of 2.5.
Homework Statement
A fisherman sets out upstream on a river. His small boat, powered by an outboard motor, travels at a constant speed v in still water. The water flows at a lower constant speed vw. The fisherman has traveled upstream for 1.85 km when his ice chest falls out of the boat. He...
One dimensional motion-- object accelerating straight downwards
Homework Statement
A rocket, initially at rest, is fired at "t = 0" vertically down from a building of height "H". The rocket's acceleration, including the effects of gravity, is downwards with increasing magnitude given by a(t)...
A car moving at 187km/h is behind a truck that's moving at 71km/h and is 150m ahead of the car
How long will it take the car to catch the truck ?
I'm literally in 2 lectures in my physics 101 class but I figure it would be cool to take a shot at the problem. This is what I did...
Homework Statement
A person travels by car from one city to another with different constant speeds between pairs of cities. She drives for 45.0 min at 55.0 km/h, 17.0 min at 65 km/h, and 60.0 min at 30.0 km/h, and spends 55.0 min eating lunch and buying gas.
(a) Determine the average speed...
Homework Statement
Hi, Physics Forum!
I have three problems. Since I am having a physics final on Tuesday, I am very nervous that I don't get these. These all concern one-dimensional motion.
1.) A plane is landing on the runway. It stops after 1100 meters, with an initial velocity of 110...
Homework Statement
Two trains, each having a speed of 30 miles/hr, are headed at
each other on the same straight track. A bird that can fly 60 miles/hr flies
off one train when they are 60 miles apart and heads directly for the other
train. On reaching the other train it flies directly...
Homework Statement
Vehicle one driving 30 m/s. Slow moving vehicle 155 m ahead driving 5.00 m/s. Vehicle one brakes and decelerates at -2.00 m/s2. Is there a collision? If not what's the closest they get?
Homework Equations
Vehicle one info:
Vi= 30 m/s
A= -2 m/s2
\DeltaX= 155 m...
Hi this problem is one I couldn't understand very well so I couldn't do big attempts at solving
Homework Statement
since I have it on pdf and I don't want to mistake in typing and that there is a picture in it I made the problem into a picture...
Homework Statement
A car accelerates uniformly from rest to a speed of 40 mi/h in 12.0 secs find A) the distance the car traveled during this time and B) the constant accelaration of the car
Homework Equations
a) Displacement of an object as a function of time: delta x =1/2(v0+v)T
B)...
Homework Statement
1) Runner A is initially 4.0 mi west of a flagpole and is running with a constant velocity of 6.0 mi/h due east. Runner B is initially 3.0 mi east of the flagpole and is running with a constant velocity of 5.0 mi/h due west. How far are the runners from the flagpole when...
Homework Statement
A baseball pticher throws a baseball with a speed of 44 m/s. Estimate the average acceleration of the ball drugin the trowing motion. It is observed that in throwing the baseball, the pitcher accelerates the ball through a dsiplacement of about 3.5 m, from behind the body...
Homework Statement
A toy rocket passes by a 2.0 m-high window whose sill is 10.0 m above the ground. The rocket takes .15 s to travel the 2.0 m height of the window. What was the launch speed of the rocket, and how high will it go? Assume the propeltant is burned very quickly at blastoff...
I know this problem has been posted before, but I think my answer is correct and I want to know why it was considered wrong!
Homework Statement
Cars A and B are racing each other along the same straight road in the following manner: Car A has a head start and is a distance Da beyond the...
Homework Statement
A rock is thrown vertically upward with a speed of 12.0 s^-1 m. Exactly 1.00 s later, a ball is thrown up vertically along the same path with a speed of 20.0 s^-1 m.
(a) At what time will they strike each other?
(b) At what height will the collision occur...
Homework Statement
A runner hopes to complet the 10,000 m run in less than 30.0 min. After running at constant speed for exactly 27.0 min, there are still 1100 m to go. The runner must tehn acceelerate at .20 s^2 m for how many seconds in order to achieve teh desired time?
Homework...
Homework Statement
Challenge Problem(2.96) from University Physics textbook:
In the vertical jump, an athlete starts from a crouch and jumps upward to reach as high as possible. Even the best athletes spend little more than 1.00s in the air (their "hang time"). Treat the athlete as a particle...
a particle moves along the x-axis. its position is given by the equation x=2+3t-4t^2
determine its position when it changes direction.
and its velocity when it returns to the position it had at t=0
Hey everyone,
Well, I am sort of stuck on this problem:
Two trains, one traveling at 78 km/h and the other at 135 km/h, are headed toward one another along a straight, level track. When they are 980 m apart, each engineer sees the other's train and applies the brakes. The brakes decelerate...
Hello,
I was wondering if someone could help me out with this one. Its been years since I've done physics and this problems is bugging the hell out of me.
Thanks
An object is moving in a straight line with a constant acceleration. Its position is measured at three different times, as shown in the table below.
Time (s) | Position, (m)
56.40 | 9.700
58.20 | 19.042
60.00 | 38.428
Calculate the magnitude of the acceleration at t=58.20 s
I am not...
can anyone help me with this problem please--
A tortoise can run with a speed of 0.10 m/s and a hare can run 20 times as fast. in a race they both start at the same time but the hare stops to rest for 2.0 minutes. the tortoise wins by 20 cm.
how long does the race take?
what is the...