- #1
Dantex460
- 1
- 0
Hello this is my last questions i have to finish the year, the problem I'm having is finding the correct way to work it out. I've looked at others but there their problem has differences and what units to use.
A vehicle of mass 750kg accelerates up an incline of 1 in 10 (sine) increasing its speed from 20 kmh^-1 to 60 kmh^-1 in a time of 8.5 second; if the frictional resistance to motion is 0.5kN. making use of D'alembert's principles; Determine:
1. the tractive effort between the driving wheels and the road surface.
2. the work done during the period of acceleration
3. the average power developed
4. use energy method to confirm your answers in 2.
1. tractive effort = change in ke + change in pe
pe= mgh
ke= 1/2MV
initial ke = mass/2 x v(intial time)^2
final ke = mass/2 x v(end time)^2
time taken = change in velocity/acceleration
work done = fs
power = work done/time taken
1. tractive effort
initial Ke = 750kg/2 x (no initial time so i used 1) = 375
final Ke = 750kg/2 x 8.5^2 = 27093.75
change in Ke = 27093 - 375 = 26718
Pe = 750 x 9.81 x 40sin( I'm not sure how to get height
2. work done = f x (20kmh - 60kmh) = f x 40kmh
acceleration = v^2(final time) - (time taken)8.5^2/2s
f = 750kg x acceleration
3. power = work/8.5s
Thank you very much for any help in advanced.
Homework Statement
A vehicle of mass 750kg accelerates up an incline of 1 in 10 (sine) increasing its speed from 20 kmh^-1 to 60 kmh^-1 in a time of 8.5 second; if the frictional resistance to motion is 0.5kN. making use of D'alembert's principles; Determine:
1. the tractive effort between the driving wheels and the road surface.
2. the work done during the period of acceleration
3. the average power developed
4. use energy method to confirm your answers in 2.
Homework Equations
1. tractive effort = change in ke + change in pe
pe= mgh
ke= 1/2MV
initial ke = mass/2 x v(intial time)^2
final ke = mass/2 x v(end time)^2
time taken = change in velocity/acceleration
work done = fs
power = work done/time taken
The Attempt at a Solution
1. tractive effort
initial Ke = 750kg/2 x (no initial time so i used 1) = 375
final Ke = 750kg/2 x 8.5^2 = 27093.75
change in Ke = 27093 - 375 = 26718
Pe = 750 x 9.81 x 40sin( I'm not sure how to get height
2. work done = f x (20kmh - 60kmh) = f x 40kmh
acceleration = v^2(final time) - (time taken)8.5^2/2s
f = 750kg x acceleration
3. power = work/8.5s
Thank you very much for any help in advanced.
Last edited: