EHV A class 3

Multiple Choice

Which force component in vehicle kinetics is positive when climbing a grade?

• Rolling resistance

• Aerodynamic drag

• Gravitational force along slope

• None of the above

Multiple Choice

Aerodynamic drag force is proportional to:

• Velocity V

• v²

• v³

• 1/v

Multiple Choice

The tractive power at the wheels is given by:

• P_TR​=F_TR​⋅v

• P_TR​=T_TR​⋅ω_wh​

• Both a & b

• None of the above

Multiple Choice

An EV with C_D=0.28 , A_F=2.4 m², and ρ=1.225 kg/m³ travels at 90 km/h. The aerodynamic drag force is closest to:

• 278 N

• 312 N

• 340 N

• 370 N

Multiple Choice

A higher motor speed relative to vehicle speed generally:

• Reduces gear ratio and cost

• Increases gear ratio and size

• Has no effect on cost

• Eliminates the need for a gearbox

Multiple Choice

The terminal velocity for constant F_TR​ on level road is reached when:

• F_TR​=0

• F_TR​=F_RL​

• v=0

• a=g

Multiple Choice

The main advantage of a long constant power region in traction motor design is:

• Reduced top speed

• Increased acceleration and gradeability

• Increased rolling resistance

• Need for more gears

Multiple Choice

In an in-wheel direct drive without gearing, the motor must:

• Deliver higher torque to start and accelerate

• Operate only at high speeds

• Use multi-speed gearboxes

• Avoid regenerative braking

Multiple Choice

On a flat road, if  F_TR​=2000 N and v=20 m/s , the tractive power is:

• 10 kW

• 20 kW

• 80 kW

• 40 kW

Multiple Choice

A vehicle of mass 1500 kg is on a 5% grade. The gravitational force component along the slope is:

• 735 N

• 750 N

• 7350 N

• 75 N