How Do You Calculate Average Speed in Different Driving Conditions?

In summary: Velocity's . So average velocity is just the distance traveled divided by the time it took to travel it .In summary, on the way to Houston, the driver travels at a speed of 103 km/h in the first half and at 58 km/h in the second half. On the way back, they travel at 103 km/h in the first half and 58 km/h in the second half. The total distance traveled is 80.5 kilometers.
  • #1
hiineko
63
1

Homework Statement


You drive on Interstate 10 from San Antonio to Houston, half the time at 58 km/h and the other half at 103 km/h. On the way back you travel half the distance at 58 km/h and the other half at 103 km/h. What is your average speed (a) from San Antonio to Houston, (b) from Houston back to San Antonio, and (c) for the entire trip? (d) What is your average velocity for the entire trip?

Homework Equations


V=d/t[/B]

The Attempt at a Solution


with a help of a friend online but I still don't understand it.
a.) (58*t/2 + 103*t/2) / t = 58/2+103/2 = (58+103)/2 = 80.5 The problem is I don't know how did "t" gone
b.) D/(D/2/(58))+(D/2/(103)) = ??
c.) none, stuck in A and B so can't answer this
d.) I don't why "zero" is the answer here pls explain

Help pls
I kinda suck at Algebra which lead to sucking in Physics too lol
 
Last edited:
Physics news on Phys.org
  • #2
hiineko said:
a.) (58*t/2 + 103*t/2) / t = 58/2+103/2 = (58+103)/2 = 80.5 The problem is I don't know how did "t" gone
If it hadn't gone, you couldn't have solved the equation because you have no information about the duration of the trip.

hiineko said:
b.) D/(D/2/(58))+(D/2/(103)) = ??
What is the problem here? This equation is correct, you just have to solve it.

hiineko said:
c.) none stuck
You have to use the same equation: v=d/t. What is the distance and time if we look at the entire trip? As you don't have exact data about these, you have to express them somehow and hope that the unknown cancels :D.

hiineko said:
d.) I don't why "zero" is the answer here pls explain
What is the difference between speed and velocity?
 
  • #3
hiineko said:

The Attempt at a Solution


with a help of a friend online but I still don't understand it.
a.) (58*t/2 + 103*t/2) / t = 58/2+103/2 = (58+103)/2 = 80.5 The problem is I don't know how did "t" gone
b.) D/(D/2/(58))+(D/2/(103)) = ??
c.) none stuck
d.) I don't why "zero" is the answer here pls explain

Help pls
I kinda suck at Algebra which lead to sucking in Physics too lol
Do you know what average speed and velocity is ? What exactly is your doubt ? What do you mean by none stuck ?
 
  • #4
Qwertywerty said:
Do you know what average speed and velocity is ? What exactly is your doubt ? What do you mean by none stuck ?

Sorry I meant to say no answer because I got stuck to letter a and b.

my doubt is I'm lacking knowledge of doing it algebraically.
especially in letter A I mean how did t has cancel or eliminated
 
  • #5
Robin04 said:
If it hadn't gone, you couldn't have solved the equation because you have no information about the duration of the trip.What is the problem here? This equation is correct, you just have to solve it.You have to use the same equation: v=d/t. What is the distance and time if we look at the entire trip? As you don't have exact data about these, you have to express them somehow and hope that the unknown cancels :D.What is the difference between speed and velocity?

Letter A. So can you explain how did "t" got cancel or eliminated
Letter B. Can you lend me a hand of doing it?
Letter C. I'll deal with later because I need the answer of A and B to answer this
Letter D. Hmmm none?
 
  • #6
Average speed is defined as the distance traveled in some particular time . Often , when you move , your speed is not constant , and tends to change . So we define average speed , to refer to the average distance traveled per unit time .

Post edited .
 
Last edited:
  • #7
Part D - Average velocity is net displacement ( in a certain time interval ) upon time interval considered . What is net diplacement when you leave SA , and then come back to SA ?

Part C , involves some calculation .

Hope this helps .
 
  • #8
Qwertywerty said:
Part D - Average velocity is net displacement ( in a certain time interval ) upon time interval considered . What is net diplacement when you leave SA , and then come back to SA ?

Part C , involves some calculation .

Hope this helps .

Okayy I got letter D thankyou!
Sir problem is I can't do it algebraically especially A look the first post above, I don't know how t got cancel.
 
  • #9
hiineko said:
Sir problem is I can't do it algebraically especially A look the first post above, I don't know how t got cancel
Ok , yes I had made a mistake in my earlier post .
Corrected - let time taken to reach H be t . First half , with speed v1 and second half with v2 .

So , for t/2 , car ( I assume ) travels a distance v1*t/2 , and the second t/2 , v2*t/2 .
So total distance traveled is equal to v1*t/2 + v2*t/2 = ( v1/2 + v2/2 )*t ←taking t out common .

Now , average speed = ( v1/2 + v2/2 )*t/t ←formula of average speed .
Can you now cancel t ?

I hope this is clear enough . If not , feel free to ask what is not .
 
  • #10
Qwertywerty said:
Ok , yes I had made a mistake in my earlier post .
Corrected - let time taken to reach H be t . First half , with speed v1 and second half with v2 .

So , for t/2 , car ( I assume ) travels a distance v1*t/2 , and the second t/2 , v2*t/2 .
So total distance traveled is equal to v1*t/2 + v2*t/2 = ( v1/2 + v2/2 )*t ←taking t out common .

Now , average speed = ( v1/2 + v2/2 )*t/t ←formula of average speed .
Can you now cancel t ?

I hope this is clear enough . If not , feel free to ask what is not .

Wow thankyou! That was so clear. Thankyou thankyou! I'll update you again if I have more questions. Good day sir
 

Related to How Do You Calculate Average Speed in Different Driving Conditions?

What is kinematics?

Kinematics is the branch of physics that studies the motion of objects without considering the forces causing the motion. It involves analyzing the position, velocity, and acceleration of an object over time.

What is average speed?

Average speed is the total distance traveled divided by the total time it takes to travel that distance. It is a measure of how fast an object is moving on average.

How do you calculate average speed?

Average speed can be calculated by dividing the total distance traveled by the total time it takes to travel that distance. This can be represented by the equation: average speed = total distance / total time.

What is the difference between speed and velocity?

Speed is a measure of how fast an object is moving, while velocity is a measure of the speed and direction of an object's motion. Velocity takes into account the direction of an object's movement, while speed does not.

What is the difference between average speed and instantaneous speed?

Average speed is the total distance traveled divided by the total time, while instantaneous speed is the speed at a specific moment in time. Average speed gives an overall measure of an object's speed, while instantaneous speed gives the speed at a particular point in time.

Similar threads

  • Introductory Physics Homework Help
Replies
4
Views
1K
  • Introductory Physics Homework Help
Replies
22
Views
1K
  • Introductory Physics Homework Help
Replies
4
Views
17K
  • Introductory Physics Homework Help
Replies
1
Views
2K
  • Introductory Physics Homework Help
Replies
1
Views
1K
  • Introductory Physics Homework Help
Replies
13
Views
1K
  • Introductory Physics Homework Help
Replies
8
Views
2K
  • Introductory Physics Homework Help
Replies
5
Views
4K
  • Introductory Physics Homework Help
Replies
3
Views
1K
  • Introductory Physics Homework Help
2
Replies
40
Views
6K
Back
Top