# Electric Vehicles | Week 4

**Course Name: Electric Vehicles – Part 1**

**Course Link: Click Here**

**These are Electric Vehicles Week 4 Assignment 4 Answers NPTEL**

**These are Electric Vehicles Week 4 Assignment 4 Answers NPTEL****For Question 1 to 4 – **

**Consider an EV with the following details. Tire rolling friction coefficient = 0.01, Ratio of Gear ratio to the radius of the tyres = 15, acceleration due to gravity = 9.8 m/s ^{2} . Equivalent mass for rotational mass can be taken as 5% of total mass. The wheel is connected to a three phase induction motor with a gear. The maximum torque of the motor is 200 Nm. The maximum percentage grade of the vehicle is 25.EV starts from rest and operates in constant torque region. Aerodynamic force is neglected. Rated speed of the motor is 5639 rpm.**

**Q1. Tractive effort is**

a. 2000 N

b. 1000 N

c. 3000 N

d. 1500 N

**Answer: c. 3000 N**

**Q2. Mass of EV is**

a. 1236 kg

b. 1262 kg

c. 1200 kg

d. 1365 N

**Answer: b. 1262 kg**

**These are Electric Vehicles Week 4 Assignment 4 Answers NPTEL**

**Q3. Acceleration is**

a. 2.2 m/s2

b. 1.8 m/s2

c. 1.2 m/s2

d. 2.6 m/s2

**Answer: a. 2.2 m/s2**

**Q4. Power rating of the motor**

a. 117.5 kW

b. 116.8 kW

c. 118.1 kW

d. 120 kW

**Answer: c. 118.1 kW**

**These are Electric Vehicles Week 4 Assignment 4 Answers NPTEL**

**For Questions 5 to10 – **

**Consider an EV with the following details. Total mass = 1200 kg, front area = 2 m ^{2}, aerodynamic drag coefficient = 0.25 and tire rolling friction coefficient = 0.02, air density = 1.25 kg/m^{3} , acceleration due to gravity = 10 m/s^{2} . Equivalent mass for rotational mass can be taken as 6% of total mass. The wheel is connected to a three phase induction motor with a gear. Gear efficiency is 0.9. Induction motor is operating in constant torque region. The vehicle starts from rest and linearly reaches velocity of 80 km/hr in 10 seconds.**

**Q5. Tractive effort at 10 sec is**

3218.1 N

3058.3 N

10570.3 N

3232.54 N

**Answer: 3218.1 N**

**Q6. Power at the wheels is**

7144 W

64.4 kW

6429.6 W

71.5 kW

**Answer: 71.5 kW**

**These are Electric Vehicles Week 4 Assignment 4 Answers NPTEL**

**Q7. Power at the motor shaft is**

71.56 kW

71.56 kW

79.5 kW

7937.78 W

**Answer: 79.5 kW**

**Q8. Percentage grade of the vehicle is**

26.2

27.8

26.36

24.77

**Answer: 27.8**

**These are Electric Vehicles Week 4 Assignment 4 Answers NPTEL**

**Q9. Speed of the motor at 3 seconds is**

24 m/sec

2400 m/sec

666.6 m/sec

6.7 m/sec

**Answer: 6.7 m/sec**

**These are Electric Vehicles Week 4 Assignment 4 Answers NPTEL**

**Q10. Tractive effort at 5 seconds is**

2942.5 N

3218.13 N

3102.3 N

3058.3 N

**Answer: 3102.3 N**

**These are Electric Vehicles Week 4 Assignment 4 Answers NPTEL**

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