In everyday use and in kinematics, the speed (commonly referred to as v) of an object is the magnitude of the rate of change of its position with time or the magnitude of the change of its position per unit of time; it is thus a scalar quantity. The average speed of an object in an interval of time is the distance travelled by the object divided by the duration of the interval; the instantaneous speed is the limit of the average speed as the duration of the time interval approaches zero.
Speed has the dimensions of distance divided by time. The SI unit of speed is the metre per second (m/s), but the most common unit of speed in everyday usage is the kilometre per hour (km/h) or, in the US and the UK, miles per hour (mph). For air and marine travel the knot is commonly used.
The fastest possible speed at which energy or information can travel, according to special relativity, is the speed of light in a vacuum c = 299792458 metres per second (approximately 1079000000 km/h or 671000000 mph). Matter cannot quite reach the speed of light, as this would require an infinite amount of energy. In relativity physics, the concept of rapidity replaces the classical idea of speed.
Homework Statement
Any person on the Earth is carried in a cirular path as the Earth rotates on axis. The Earth revolves once in a day. At a latitude of Φ, the distance to the axis of rotation is R = REarthcos(Φ). If Anytown's latitude is 48.8 degrees and the Earth's radius is 6378 km, what is...
Homework Statement
An electron moves in the positive x-direction a distance of 2.44 m in 3.10 *10-8 s, bounces off a moving proton, and then moves in the opposite direction a distance of 1.68 m in 3.53*10-8 s.
The Attempt at a Solution
to find the average velocity I used the distance...
Homework Statement
The space shuttle takes off from Cape Canaveral in Florida and orbits Earth 18 times before landing back at Cape Canaveral 23 hours and 7 minutes later. During this time, it moves in circular orbit with radius 6.6 x10^6 m.
Homework Equations
The equation that I am...
Homework Statement
Suppose that you loft the ball with an initial speed of v = 13.5 m/s, at an angle of θ = 48.5° above the horizontal. At this instant your opponent is d = 10.0 m away from the ball. He begins moving away from you 0.350 s later, hoping to reach the ball and hit it back at...
Homework Statement
Hi
I read a question recently on the British Mensa website and I thought the answer was 112.5mph. The answer given was 108mph. What is the calculation for this scenario?
"Lap 1 is completed at 135mph, lap 2 is completed at 90mph, what’s the average speed?"...
Homework Statement
On certain days, traveling to Balamb from Galbadia using a bus takes an average speed of 70 km/hr. The trip takes about 18 minutes. On a busy traffic day, the drive slows down to 40 km/hr over the same distance. How much longer does the trip takes?
Thanks
What can be said about average speed relative to the magnitude of the average velocity?
a) greater than
B) equal to
C)both a and B
I think it is neither because average velocity is displacement/total time and average speed is distance/total time.
Since displacement is always equal to or...
Hey,
This is kinda a thick question but never mind.
A car travels 30KM and that for 30mins.
What is the average speed of the car?Formula is Average speed= Distance Travelled DIVIDED BY Time taken.
But its not 30 DIVIDED by 30 is it?
Is it 30 DIVIDED by 0.5 as 30mins is half of an hour?
And how...
Homework Statement
Andrew won a two day bicycle race. He traveled 60km each day and his average speed on the second day was double that of the first day. If Andrew rode for a total of 6 hours, what was his average speed each day?
a) state an equation that models this problem.
b) Solve the...
Homework Statement
Jake is 1 mile per hour faster on his skateboard than Tom. Both skate 24 miles one day from the park to the mall. Tom took 2 hours longer than Jake. What was Tom's average speed?
Homework Equations
d=rt
The Attempt at a Solution
So I set up a table w/ d=24, rate...
Homework Statement
A person travels by car from one city to another with different constant speeds between a pair of cities. She drives for 30.3 min at 85.2 km/h, 14.4 min at 91.1 km/h, and 48.9 min at 43.1 km/h, and spends 19.1 min eating lunch and buying gas. The distance between the initial...
Homework Statement
(a) A particle has a displacement r1 = (35.0i + 12.0j + 14.0k) m at 29.0 s. At 53.0 s the ball has a displacement of r2 = (35.0i + 6.0j + 11.0k) m.
What is the average speed of the ball between 29.0 s and 53.0 s?
The Attempt at a Solution
Having checked the...
Homework Statement
A group of physics students take off in a small plane to visit physics Land. The plan flies at a constant speed of 160 mph. They start at Newtonville and travel 160 miles due north to Faraday Town. At this point they change course for Maxwell City, which is 320 miles away...
Homework Statement
a) A journey is completed by travailing for the first half of the time at speed V1 and the second half at speed V2. Find the average speed Va for the journey in terms of V1 and V2 .
b) A journey is completed by traveling at speed V1 for half the distance and at speed V2...
Homework Statement
You jog at 9.5 km/hr for 8.0 km. You jump into a car and drive 16 km. What speed of the car do you need to cover a total distance of 24 km with an average speed of 22 km/hr
Homework Equations
The Attempt at a Solution
average speed help!
Homework Statement
On your wedding day you leave for church 33.0 minutes before the ceremony is to begin, which should be plenty of time since the church is only 10.5 miles away. On the way, however, you have to make an unanticipated stop for construction work on the...
Homework Statement
Given that the integral [between infinity and 0] v3e-av2dv = 1/2a2
calculate the average speed vav of molecules in the gas using the maxwell-boltzmann distribution function
Homework Equations
The Attempt at a Solution
i don't really know what to do some...
If a car travels at a distance of x^3+60x^2+x+60 miles at an average speed of x+60 miles per hour, how long does the trip take??
not sure how to solve this problem either, Its in the whole chapter of dividing polynomials, so I tried dividing .. it all just basically said that it was a...
Homework Statement
http://img406.imageshack.us/img406/6418/problemo.jpg Homework Equations
<V>=( Integral-from-0-to-inf(V*f(V)*dV) ) / ( Integral-from-0-to-inf (f(V)*dV) )
(second integral is for normalisation)The Attempt at a Solution
http://img32.imageshack.us/img32/529/thermalphysics.jpg
Homework Statement
It takes 2 minutes to fill a gas tank with 40 liters of gasoline. If the nozzle is 1cm in radius, what is the average speed of the gasoline as it leaves the nozzle?
Homework Equations
A1V1=A2v2 or 1/2pv^2 + pgh+p=constant
The Attempt at a Solution
I don't really...
Hi everyone,
http://img372.imageshack.us/img372/6093/img009h.jpg
With the above, I really have no idea other than the standard s=d/t formula, but I doubt that has anything to do with it for a question worth 3 marks, and then looking at the two questions below, it'd make no sense.
The...
Homework Statement
Sally travels by car from one city to another. She drives for 30.0 min at 52.0 km/h, 35.0 min at 48.0 km/h, and 23.0 min at 50.0 km/h, and she spends 10.0 min eating lunch and buying gas.
Homework Equations
avg. speed= distance traveled / time of travel
The...
[b]1. We drive a distance of 1 kilometer at 14 km/h. Then we drive an additional distance of 1 kilometer at 30 km/h. What is our average speed?
[b]2. average speed= total distance / total time
[b] 3. 22mp/h
Homework Statement
I need to determine the average speed of a dot on a spinning motor and also the time it takes for teh dot to make on revolution. Using a strobe light I determined I needed to do 3959.2 flashes/min in order to make the dot stay in place. The dot is 6.9 cm away from the center...
Homework Statement
Calculate the average speed of a complete round trip in which the first 148.6 km is covered at 84.6 km/hr, followed by a 1.2-hour lunch and the final 148.6 km is covered at 50.6 km/hr.
Homework Equations
The Attempt at a Solution
148.6+148.6/.569+1.2+.341 =...
Homework Statement
Sally travels by care from on city to another. She drives for 30.0 min at 80.0 km/h, 12.0 min at 105 km/h, and 45.0 min at 40. km/h, and she spends 15.0 min eating lunch and buying gas.
a.) Determine the average speed for the trip.
b.) Determine the total disance traveled...
Homework Statement
(a) If the maximum acceleration that is tolerable for passengers in a subway train is 1.54 m/s2 and subway stations are located 816 m apart, what is the maximum speed a subway train can attain between stations? (b) What is the travel time between stations? (c) If a subway...
Homework Statement
A car travels up a hill at a constant speed of 32 km/h and returns down the hill at a constant speed of 66 km/h. Calculate the average speed (in km/h) for the round trip.Homework Equations
average speed= total distance/ delta time is the only equation i know for it
The...
[b]1. 1. To get to a concert in time, a harpsichordist has to drive 124 miles in 2.01 hours.
(a) If he drove at an average speed of 53.0 mi/h in a due west direction for the first 1.18 h, what must be his average speed if he is heading 30.0° south of west for the remaining 49.8 min?
(b)...
[b]1. To get to a concert in time, a harpsichordist has to drive 124 miles in 2.01 hours.
(a) If he drove at an average speed of 53.0 mi/h in a due west direction for the first 1.18 h, what must be his average speed if he is heading 30.0° south of west for the remaining 49.8 min?
(b)...
Homework Statement
A person walks from point a to point b at a speed of 5 m/s. Then she turns around and walks from point b to point a at a speed of 3 m/s. What is her average speed?
Homework Equations
Average speed is equal to d/ change in t.
The Attempt at a Solution
So I know...
Homework Statement
You plan a trip on which you want to average 97.2 kilometers per hour. You cover the first half of the distance at an average speed of only 72.5 kilometers per hour. What must your average speed be in the second half of the trip to meet your goal? Hint: Pick a distance...
I just wanted to know how to find average speed without knowing the distance. I know average speed is defined as total distance / change in time but what would you do
a person travels to a friend's house and when he is halfway there, he figures out that he has been averaging 30 mph. He drives...
Homework Statement
A baseball is hit into the air at an initial speed of 36.6m/s and an angle of 50degrees above the horizontal. At the same time, the center fielder starts running away from the batter and catches the ball 0.914m above the level at which it was hit. If the center fielder is...
obviously the root-means-square speed value is greater than the average value.
Question is to why the root-mean-square speed is taken as a kind of average speed for gases but formula used in statistic in getting average number ?
As when the number is squared, the final average value is...
Homework Statement
A race car races on a circular racetrack of radius (r).
(a) Write an equation for the car’s average speed when it travels a complete lap in time (t).
(b) The radius of the track is 400m and the time to make a lap is 40s. Show that the average speed around the track is 63m/s...
A billiard ball travels 0.44m [S] from its original position, bounces off another ball and travels 0.88m [N], then bounces off the edge of the billiard table coming to rest 0.12m from that edge. The entire motion is one-dimentional and takes 2.4s. (a) calculate the average speed of the ball...
Homework Statement
A car is making a trip of 40 mi. It travels half the distance at an average speed of 20 mph. In order for it to have an average speed of 40 mph for the whole trip, the car would need to:
a. travel at an average speed of 40 mph for the trip’s remainder.
b. travel at an...
?Average speed??
Homework Statement
As you have calculated, the average speed of an air molecule at room temperature is about 500 m/s. What is deltaR rms (root means squared) for an air molecule after five seconds?
answer is in mm
not even sure what mm is other than millimeters...
Is there a difference between "mean speed " and "average speed"?
Is there a difference between mean speed and average speed? The words "mean" and "average" seem to mean the same thing.
Homework Statement
A golfer rides in a golf cart at a speed of 3.10 m/s for 24.0 s. She then gets out of the cart and starts walking at an average speed of 1.30 m/s. For how long (in seconds) must she walk if her average speed for the entire trip, riding and walking, is 1.90 m/s...
[b]1. You plan a trip on which you want to average 90 km/hr. You cover the first half of the distance at an average speed of only 48 km/hr. What must your average speed be in the second half of the trip to meet your goal? Note that the velocities are based on half the distance, not half the...
Homework Statement
A mobile is moving straight as following: the first portion of the road, equal to 10% of the total distance with the speed v1=10/s , and the rest with the speed v2=30m/s.
The average speed for the entire trip is?
a)25m/s b)22.5m/s c)20m/s d)15m/s
Homework Equations...
Homework Statement
A boat moves 15.0 km across a lake in 30.0 min. What was the average speed of the boat in kilometers per hour?
Homework Equations
average speed: d/t
The Attempt at a Solution
ok since it is asking kilometers per hour that is the part tha confuses me.
i mean i...
A car travels 50km at 30degrees North of East for 20min, then 30km at 70degrees North of East with speed of 20km/hr, then another 10km at 60degrees North of East with speed 80km/hr. Find
A)Total distance traveled
B)The average speed of the car
C)The displacement of the car(magnitude and the...
Im having a rough time with this set of problems in general, so instead of creating a lot of threads I am just going to keep adding what I have here. I am not looking for the answers to my homework, just some guidance and my mistakes pointed out. I appreciate any and all input I receive...
Homework Statement
What is the definition of average speed? How is average speed different from instantaneous speed? Explain.Homework Equations
noneThe Attempt at a Solution
Average speed is covering an equal amount of distance in an equal amount of time. Instantaneous speed, however, is speed...
Hello everyone! I am really terrible at physics.
I genuinely tried doing them(looking for similar examples in the book and such), but am still stuck. If someone could point me in the right direction, I'd appreciate it. Thanks in advance!
1) A car is making a 12 mile trip. It travels the...
Homework Statement
A person walks first at a constant speed of 47.0m/s along a straight line from point A to point B and then back along the line from B to A at a constant speed of 3.10m/s
Homework Equations
What is her average speed over the entire trip?
The Attempt at a Solution...