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Goryan [66]
3 years ago
9

Suppose a car manufacturer tested its cars for front-en4 collisions by hauling them up on a crane and dropping then; from a cert

ain height, (a) Show that the speed just before a car hits the ground, after falling from rest a vertical distance H, is given by \/2 g H . What height corresponds tq a collision at (b) 50 km/h
Physics
1 answer:
Brrunno [24]3 years ago
6 0

Answer:

a

Generally from third equation of motion we have that

v^2 =  u^2 + 2a[s_i - s_f]

Here v is the final speed of the car

u is the initial speed of the car which is zero

s_i is the initial position of the car which is certain height H

s_i is the final position of the car which is zero meters (i.e the ground)

a is the acceleration due to gravity which is g

So

v^2 = 0 + 2g[H - 0]

=> v  =  \sqrt{ 2 g H}

b

H  =  9.86 \  m

Explanation:

Generally from third equation of motion we have that

v^2 =  u^2 + 2a[s_i - s_f]

Here v is the final speed of the car

u is the initial speed of the car which is zero

s_i is the initial position of the car which is certain height H

s_i is the final position of the car which is zero meters (i.e the ground)

a is the acceleration due to gravity which is g

So

v^2 = 0 + 2g[H - 0]

=> v  =  \sqrt{ 2 g H}

When v  = 50 \  km/h = \frac{50 *1000}{3600} = 13.9 \  m/s we have that

13.9  =  \sqrt{ 2 g H}

=> H  =  \frac{13.9^2}{2 *  9.8}

=> H  =  9.86 \  m

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