Question

HURRY!!!!

Fred and Ted are racing cars down a frictionless track with a jump at the bottom
when suddenly an argument breaks out. Fred says, “If we release the cars from a
point twice as high as we are currently doing so, the cars will have twice the
gravitational potential energy, and therefore be travelling twice fast when they hit
the jump." Ted says, “In order to double the speed of the cars when they hit the
ramp, I think we will have to more than double the height!" Who is right? Prove it!

Answer 1

Ted is correct

Step-by-step explanation:

The equation for gravitational potential energy is PE = m·g·h

The equation for gravitational kinetic energy is KE = 1/2·m·v²

Where:

m = Mass of the object (The racing car)

g = Acceleration due to gravity

h = The height to which the object is raised

v = Velocity of motion of the object

From the principle of conservation of energy, energy can neither be created nor destroyed but changes from one form to another, we have;

Potential energy gained from location at height h = Kinetic energy gained as the object moves down the level ground

m·g·h = 1/2·m·v² canceling like terms gives

g·h = 1/2·v²

v = (√2·g·h)

If the speed is doubled, we have

2·v = 2× (√2·g·h) = (√2·g·4·h)

Therefore, if 2·v = v₂ then v₂ = (√2·g·4·h)

Since g, the acceleration due to gravity, is constant, it means that the initial height must be multiplied or increased 4 times to get the new height, that is we have;

v₂ = (√2·g·4·h) = (√2·g·h₂)

Where:

4·h = h₂

Which gives;

v₂² = 2·g·h₂

1/2·v₂² = g·h₂

1/2·m·v₂² = m·g·h₂ Just like in the first relation

Therefore, Ted is correct s they need to go up four times the initial height to double the speed.