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lapo4ka [179]
3 years ago
7

When jumping straight down, you can be seriously injured if you land stiff-legged. One way to avoid injury is to bend your knees

upon landing to reduce the force of the impact. A 84.0-kg man just before contact with the ground has a speed of 6.82 m/s. (a) In a stiff-legged landing he comes to a halt in 4.56 ms. Find the magnitude of the average net force that acts on him during this time. (b) When he bends his knees, he comes to a halt in 0.254 s. Find the magnitude of the average net force now. (c) During the landing, the force of the ground on the man points upward, while the force due to gravity points downward. The average net force acting on the man includes both of these forces. Taking into account the directions of the forces, find the magnitude of the force applied by the ground on the man in part (b).
Physics
1 answer:
Naya [18.7K]3 years ago
3 0

Answer:

a)  F = 1.26 10⁵ N,  b)  F = 2.255 10³ N, c)   F_ {soil} = 3078 N

Explanation:

For this exercise we will use the relationship between momentum and moment

          I = Δp

          F t = p_f -p₀

a) with stiff legs, final speed is zero, initial velocity is down

         Ft = 0-p₀

         F =  m v / t

let's calculate

         F = 84.0 6.82 / 4.56 10⁻³

         F = 1.26 10⁵ N

         

b) bending the legs

         

let's calculate

         F = 84.0 6.82 / 0.254

         F = 2.255 10³ N

     

c) It is requested to calculate the force of the ground on the man

            ∑ F = F_soil -W

           F_soil = F + W

           F_ {soil} = 2.255 103 + 84 9.8

           F_ {soil} = 3078 N

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ipn [44]

Answer:

Option B

10.36 m/s

Explanation:

Using the first given equation, then velocity=distance/time

Since distance is provided as 200 m and time, t is 19.3 seconds then substituting these figures yields

v=200/19.3=10.3626943

Rounding off to 2 decimal places, then

v=10.36 m/s

6 0
3 years ago
What do I have to do to figure out " What % of an object’s mass is above the water line if the object’s density is 0.82g/ml " wi
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Answer:

18%

Explanation:

There are two equal and opposite forces on a floating object: weight and buoyancy.

W = B

The weight of an object is its mass times gravity: W = mg

Buoyancy is the weight of the displaced fluid: W = mf g

Plugging in:

mg = mf g

m = mf

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ρV = ρf Vf

Solving for the ratio of Vf / V:

Vf / V = ρ / ρf

Given that ρ = 0.82 g/mL and ρf = 1.00 g/mL:

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That means 82% of the object's volume (and therefore, 82% of its mass, assuming uniform density) is submerged.  Which means that 18% is above the water line.

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4 years ago
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Answer:

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Explanation:

From the given information:

De la información dada:

El desplazamiento ocurrió en un vector que se mueve desde una posición inicial particular hasta el final.

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