Given A Lexus IS 350, 2010 car model specifications Engine power Pin = 234kw Top speed VT=230km ● Mass of the car = 1600kg Drag coefficient Cd = 0.274 Cross-sectional area A = 2.57m² Calculate the following a) Assume the car is moving at its top speed, if we think about forces, the force F which is pushin the car forward must win the restricting forces. The main restricting forces are air resistance F and rolling resistance of tires Fr, these forces can be calculated using the following equations. F₂ 1 v=PC&Av² F₁ = μ₂N In these equations, p is the density of air, μ, is the coefficient of rolling friction and N is the support force of the road. Let's now assume that ur 0.01 and p = 1.25 kg/m³; these are quite good approximations. Calculate the force F needed to keep the car moving at its top speed VT (Hint: at top speed, a = 0.) b) The force F we just calculated is the output force that we get out of the drivetrain, while the engine power specified by manufacturer is the input power that the engine "feeds" to the drivetrain (= gearbox, differential gear(s), driveshafts). Calculate the maximum output power Poutmax and hence the mechanical efficiency of the drivetrain. c) Now that we know the force F that we can get out of our drivetrain, let's perform some calculations about the acceleration. i: Calculate the time t needed to accelerate the car from rest to 80% of its top speed, if weneglect the resisting forces. (Hint: use impulse equation f F dt = f m dv.) ii: Calculate the distances that the car will travel during this acceleration (from 0 to 80% of topspeed). Again, neglect the resisting forces. (Hint: use kinematics a ds = v dv and remember, that F = ma.)
Given A Lexus IS 350, 2010 car model specifications Engine power Pin = 234kw Top speed VT=230km ● Mass of the car = 1600kg Drag coefficient Cd = 0.274 Cross-sectional area A = 2.57m² Calculate the following a) Assume the car is moving at its top speed, if we think about forces, the force F which is pushin the car forward must win the restricting forces. The main restricting forces are air resistance F and rolling resistance of tires Fr, these forces can be calculated using the following equations. F₂ 1 v=PC&Av² F₁ = μ₂N In these equations, p is the density of air, μ, is the coefficient of rolling friction and N is the support force of the road. Let's now assume that ur 0.01 and p = 1.25 kg/m³; these are quite good approximations. Calculate the force F needed to keep the car moving at its top speed VT (Hint: at top speed, a = 0.) b) The force F we just calculated is the output force that we get out of the drivetrain, while the engine power specified by manufacturer is the input power that the engine "feeds" to the drivetrain (= gearbox, differential gear(s), driveshafts). Calculate the maximum output power Poutmax and hence the mechanical efficiency of the drivetrain. c) Now that we know the force F that we can get out of our drivetrain, let's perform some calculations about the acceleration. i: Calculate the time t needed to accelerate the car from rest to 80% of its top speed, if weneglect the resisting forces. (Hint: use impulse equation f F dt = f m dv.) ii: Calculate the distances that the car will travel during this acceleration (from 0 to 80% of topspeed). Again, neglect the resisting forces. (Hint: use kinematics a ds = v dv and remember, that F = ma.)
Elements Of Electromagnetics
7th Edition
ISBN:9780190698614
Author:Sadiku, Matthew N. O.
Publisher:Sadiku, Matthew N. O.
ChapterMA: Math Assessment
Section: Chapter Questions
Problem 1.1MA
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Transcribed Image Text:Given A Lexus IS 350, 2010 car model specifications
Engine power Pin = 234kw
Top speed VT=230km
Mass of the car = 1600kg
Drag coefficient Cd = 0.274
Cross-sectional area A = 2.57m²
Calculate the following
a) Assume the car is moving at its top speed, if we think about forces, the force F which is pushin
the car forward must win the restricting forces. The main restricting forces are air resistance
and rolling resistance of tires Fr, these forces can be calculated using the following equations.
1
F₂
pCaAv²
F₁ = μ₂N
In these equations, p is the density of air, ur is the coefficient of rolling friction and N is the
support force of the road. Let's now assume that μ, 0.01 and p = 1.25 kg/m³; these are quite
good approximations. Calculate the force F needed to keep the car moving at its top speed VT
(Hint: at top speed, a = 0.)
b) The force F we just calculated is the output force that we get out of the drivetrain, while the
engine power specified by manufacturer is the input power that the engine "feeds" to the
drivetrain (= gearbox, differential gear(s), driveshafts). Calculate the maximum output power
Poutmax and hence the mechanical efficiency of the drivetrain.
c) Now that we know the force F that we can get out of our drivetrain, let's perform some
calculations about the acceleration.
i: Calculate the time t needed to accelerate the car from rest to 80% of its top speed, if
weneglect the resisting forces. (Hint: use impulse equation f F dt = fm dv.)
ii: Calculate the distances that the car will travel during this acceleration (from 0 to 80% of
topspeed). Again, neglect the resisting forces. (Hint: use kinematics a ds = v dv and
remember, that F = ma.)
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