The mass of Tesla Model S is 2000 kg and its engine produces
400 Nm of torque. The Mercedes-Benz S Class is 50% heavier, (MBenz= 1.5·MTesla)and the Benz engine produces 50% more torque than the Tesla. For this problem we consider those cars as solid cylinders of the same radius, rolling down the road. What is the ratio of power generated by the engines 6 seconds after a start from rest? (ratio = Tesla Model S/Benz S Class)

a) 1/2
b) 2/3
c) 1
d) 3/2
e) 9/4

Respuesta :

Answer:

The ratio of the power generated by the engines are [tex]\dfrac{2}{3}[/tex]

(b) is correct option.

Explanation:

Given that,

Mass of Tesla = 2000 Kg

Torque = 400 Nm

Mass of Mercedes = 1.5 M Tesla

The Benz engine produces 50% more torque than the Tesla.

We need to calculate the power generated by the engines 6 seconds after a start from rest

Using formula of  power

[tex]P=F\cdot v[/tex]

We know that,

[tex]v=at[/tex]

[tex]v=\dfrac{F}{m}t[/tex]

[tex]v=\dfrac{\tau}{mr}t[/tex]

Put the value of F and v in equation (I)

[tex]P=\dfrac{\tau}{r}\times\dfrac{\tau}{mr}t[/tex]

[tex]P=\dfrac{\tau^2t}{mr^2}[/tex]

Here, r and t are same for both bodies.

[tex]P\propto\dfrac{\tau^2}{m}[/tex]

We need to calculate the ratio of the power generated by the engines

Using formula of power

[tex]\dfrac{P_{T}}{P_{B}}=\dfrac{\tau_{T}^2}{m_{T}}\times\dfrac{m_{B}}{\tau_{B}}[/tex]

Put the value into the formula

[tex]\dfrac{P_{T}}{P_{B}}=\dfrac{400^2}{2000}\times\dfrac{3000}{600^2}[/tex]

[tex]\dfrac{P_{T}}{P_{B}}=\dfrac{2}{3}[/tex]

Hence, The ratio of the power generated by the engines are [tex]\dfrac{2}{3}[/tex]