Distance and Speed: Calculate Avg Speed for 80km at 100 km/h & 50km at 75 km/h

  • Thread starter Thread starter AKsamantha
  • Start date Start date
  • Tags Tags
    Speed
AI Thread Summary
To calculate the average speed for a motorist traveling 80 km at 100 km/h and 50 km at 75 km/h, the average speed formula (avg speed = total distance / total time) is applied. The total distance is 130 km, but the time taken for each segment must be calculated separately. The first segment takes 0.8 hours, and the second segment takes 0.6667 hours, leading to a total time of approximately 1.4667 hours. The correct average speed for the entire trip is approximately 88.6 km/h. This calculation emphasizes the importance of accurately determining both distance and time for average speed assessments.
AKsamantha
Messages
1
Reaction score
0

Homework Statement



A mortorist travels 80km at 100 km/h, and 50 km at 75 km/h. WHat is the average speed for the trip?

Homework Equations


I used (avg)s=distance/time


The Attempt at a Solution


I got 6.2 km/h which I know is way off.
 
Physics news on Phys.org
It's a good first step to realize that your answer is not terribly realistic.

I believe you have the right equation. The average speed is: d/t. What is the total distance travel (d=?)? The little trick will be to find out how long it took the motorist to travel this distance (t=?)?

Cheers
 
v_{avg}=\frac{\Delta x }{\Delta t}
Find how far it travels in part one and add that to how far it travels in trip 2. And do the same for t.
 
Thread 'Variable mass system : water sprayed into a moving container'

Thread 'Variable mass system : water sprayed into a moving container'

Starting with the mass considerations #m(t)# is mass of water #M_{c}# mass of container and #M(t)# mass of total system $$M(t) = M_{C} + m(t)$$ $$\Rightarrow \frac{dM(t)}{dt} = \frac{dm(t)}{dt}$$ $$P_i = Mv + u \, dm$$ $$P_f = (M + dm)(v + dv)$$ $$\Delta P = M \, dv + (v - u) \, dm$$ $$F = \frac{dP}{dt} = M \frac{dv}{dt} + (v - u) \frac{dm}{dt}$$ $$F = u \frac{dm}{dt} = \rho A u^2$$ from conservation of momentum , the cannon recoils with the same force which it applies. $$\quad \frac{dm}{dt}...
View full post »

Similar threads

Shortest distance along the shore and into the lake
Replies
6
Views
936
Problem does not make sense km/h at m/s?
Replies
7
Views
2K
Calculating Average Speed: Physics Homework Problem
Replies
13
Views
2K
What are the average speed formulas needed to solve this problem?
Replies
5
Views
5K
Do I need to consider mass in the equations?
Replies
3
Views
1K
What Is the Acceleration at 55 km/h in a Sharp Monaco GP Turn?
Replies
11
Views
2K
A person takes a trip: Find the time spent on the trip, etc.
Replies
5
Views
2K
I can't quite get this question.... (|Uav|)
Replies
8
Views
2K
How to Calculate Average Velocity with Displacement & Speed?
Replies
3
Views
2K
Calculating Train Speed Using Centripetal Force | 15° Angle, 150m Radius
Replies
3
Views
2K

Hot Threads

Recent Insights

Back
Top