A person is 1.9 m tall. Where should he place the top of a mirror on the wall so he can see the top of his head? Assume his eyes
2 answers:
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Brick is held at a position which is at height 2 m from the floor
Now it is released from rest and hit the floor after t = 4 s
Now the acceleration of the brick is given by
a)
Now in order to find the tension in the string
we can use Newton's law
part b)
Now for the pulley
moment of inertia=
m = 30 kg
R = 2 m
I =
I = 60 kg m^2
Now the angular speed just before brick collide with the floor
v = 1 m/s
Now we will have
L = angular momentum = I w =
L = 60 *
L = 30 kg m^2/s
Answer:
The height of the cliff is 121.276 m
Explanation:
Given;
initial velocity of the projectile, v₁ = 75 m/s
final velocity of the projectile, v₂ = 90 m/s
spring compression = 5 m
Apply the law of conservation of energy;
mgh₀ + ¹/₂mv₁² = mgh₂ + ¹/₂mv₂²
gh₀ + ¹/₂v₁² = gh₂ + ¹/₂v²
gh₁ - gh₂ = ¹/₂v₂² - ¹/₂v₁²
g(h₀ - h₂) = ¹/₂ (v₂² - v₁²)
h₀ - h₂ = ¹/₂g (v₂² - v₁²)
h₀ = h(cliff) + 5m
when the projectile hits the ground, Final height, h₂ = 0
Therefore, the height of the cliff is 121.276 m