Answer:
Using lighter material in car construction, improving energy efficiency by enhancing engine design or replacing the engine with more efficient technologies.
Explanation:
Using lighter materials in the car construction, reducing the potential energy required to accelerate and to move the car, as well as energy losses due to rolling friction. There is evidence of such benefits by replacing steel and aluminium parts with components made of composite materials.
Improving the design of internal combustion engines to minimize energy losses and accordingly, improving energy efficiency. A more radical approach is replacing internal combustion engines with electric engines, which offer higher efficiencies. Such conclusions can be easily inferred from model based on Work-Energy Theorem and Principle of Energy Conservation:

To calculate the ideal mechanical advantage of a lever divide the input arm by the output arm.
Mechanical advantage is the amount by which a machine can multiply an input force, calculated by dividing output Force in newtons by input force in newtons, while the ideal mechanical advantage is the mechanical advantage of a machine that has no friction, calculated by dividing the input distance by the output distance.
Answer:
88.8 m/s= Speed of wave propagation in the required mode.(3 loops)
Explanation:
When there are 3 loops.
the total length = L = 3 λ /2
⇒ λ = 2 L / 3 = 2 ( 1.11 ) / 3 = 0.74 m
Velocity = v = f λ = (120)(0.74) = 88.8 m/s
Answer:
B. twice as much kinetic energy
Explanation:
Lets take the mass of the first marble =2 m
the mass of the second marble = m
We know that velocity of particle does not depends on their mass that is the velocity of both mass will be same after dropping from the roof.
We know that kinetic energy of a mass is given as

Kinetic energy for heavier mass

Kinetic energy for light mass

KE=2 KE '
Form above two equation we can say that ,the kinetic energy for the heavier mass is twice the lighter mass.
Therefore the answer will be B.