Answer:

Explanation:
Given:
- change in stiffness constant of the spring on replacing the original springs,

- mass of the car,

- initial length of the original car-spring before compression,

- final length of the original car-spring after compression,

So, weight of the car:



<u>Now the spring constant of original spring:</u>
(since 4 springs are in parallel)


<u>So the stiffness constant of the new springs:</u>



<u>Now the height lowered:</u>
(since 4 springs are in parallel)

You'd get an extra 40/60 of the energy, or 2/3. Multiply 5/3 by the required energy to get the actual consumption.
Answer:
becuz of less friction of glass and more friction of rubber