- #1
Carrie9
- 10
- 0
- Homework Statement
- A car of 1200kg accelerates up a 10 degree incline and accelerates from 30 km/h to 90 km/h in 8 sec. What is the power needed
- Relevant Equations
- P=w/t
So my result is 102hp, but it’s not correct.
You need to show your working.Carrie9 said:Homework Statement:: A car of 1200kg accelerates up a 10 degree incline and accelerates from 30 km/h to 90 km/h in 8 sec. What is the power needed
Relevant Equations:: P=w/t
So my result is 102hp, but it’s not correct.
Carrie9 said:a=((25-8,3)/8)=2,1 m/s^2
Fg=1200(9,8)sin10=2042,1N
Fa=ma+Fg
Fa=1200(2,1)+2042,1=4562,1N
P=Fa v
P=Fa ((Vo+Vf)/2)
=75958,965 W
=102hp
I suppose yesPeroK said:If you have constant acceleration, do you have constant power?
Or, if you have constant power, do you have constant acceleration?
##P = Fv##Carrie9 said:I suppose yes
Carrie9 said:Sorry but I don’t get it
Carrie9 said:I don’t get how this changes my calculations
Carrie9 said:Relevant Equations:: P=w/t
Carrie9 said:Now I’m just confused. How do I calculate the W then? and where do I apply the forces
So I need to divide the change in kinetic energy by the time? KE=(1/2)mv^2 where m is the mass (1200kg) and v is the speed (25 and 8,3 m/s)?PeroK said:Forget forces. Power is about energy.
Carrie9 said:So I need to divide the change in kinetic energy by the time? KE=(1/2)mv^2 where m is the mass (1200kg) and v is the speed (25 and 8,3 m/s)?
am I completely lost?
Carrie9 said:So change in KE + change in PE?
PE=mg(hf-hi) where hf-hi= s sin 10
No more info, got the answer 75,7W nowPeroK said:Do you have any more information on this problem?
Either you can assume constant power; or you could assume constant acceleration and calculate the maximum power.
Carrie9 said:No more info, got the answer 75,7W now
Thank you very much for the helpPeroK said:Okay, that's the average power. Hmm.
The power increases linearly with speed, so the maximum required is ##113kW##.
The main factors that affect a car's power output when accelerating uphill include the weight of the vehicle, the incline of the road, the engine's horsepower, and the transmission's gear ratio. Other factors such as air resistance and road conditions can also play a role.
Power output is calculated by multiplying the torque (force) produced by the engine with the engine's rotational speed. This is usually measured in horsepower (hp) or kilowatts (kW). The power output can also be affected by factors such as engine efficiency and friction.
Power is the rate at which work is done, while torque is the turning force produced by the engine. In simpler terms, power determines how fast a car can accelerate, while torque determines how much weight it can tow or climb.
When a car is driving uphill, it needs to overcome the force of gravity pulling it down. This means that the engine needs to produce more power to maintain the same speed as it would on a flat road. The steeper the incline, the more power is needed.
Yes, there are a few ways to improve a car's power output when accelerating uphill. Upgrading the engine with more horsepower, using a lower gear ratio, and reducing the weight of the vehicle can all help improve power output. However, it's important to note that these changes may also affect the car's fuel efficiency and overall performance.