1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
mel-nik [20]
2 years ago
8

The maximum energy a bone can absorb without breaking is surprisingly small. For a healthy human of mass 60 kg60 kg, experimenta

l data show that the leg bones can absorb about 200 J.
Required:
a. From what maximum height could a person jump and land rigidly upright on both feet without breaking his legs? Assume that all energy is absorbed in the leg bones in a rigid landing.
b. People jump from much greater heights than this; explain how this is possible.
Physics
1 answer:
netineya [11]2 years ago
5 0

Answer:

<em>the maximum height a man can jump from and land rigidly upright on both feet without breaking his legs is 0.34 m</em>

<em></em>

Explanation:

Mass of a healthy man = 60 kg

energy the bone can take without breaking = 200 J

If a healthy man jumps from a height 'h', he falls with an energy equal to the potential energy due to his initial height above the ground.

initial potential energy of the healthy man = mgh

where m = mass of the man

g = acceleration due to gravity = 9.81 m/s^2

h = the height above ground

==> PE = 60 x 9.81 x h = 588.6h

If we assume that all energy is absorbed in the leg bones in a rigid landing, then we can safely say that this calculated PE for a healthy man is equal to the energy his bone can absorb in the jump without breaking.

equating, we have

200 = 588.6h

<em>the maximum height a man can jump from without breaking his legs = 200/588.6 = 0.34 m</em>

When people jump from a height, the sudden deceleration to zero can impact a big force on the leg bones, shattering them. If the time spent in decelerating to zero is increased, the overall force on the leg bones is reduced greatly.

<em>Bending the knees gradually on landing from a jump from a height, and then rolling increases the time spent decelerating, and reduces the impact force on the legs due to the landing</em>. If you observe carefully you will see that this is what professional stunts men and acrobats do when they jump from a height.

You might be interested in
Can someone help me pls!!
Katen [24]

Answer:

Decelerating

Explanation:

One arrow is moving it forward but the other arrow is using more force to move it backwards causing it to have a reduction in speed.

5 0
3 years ago
A baseball with a mass of 151 g is thrown horizontally with a speed of 40.3 m/s (90 mi/h) at a bat. The ball is in contact with
Ghella [55]

Answer:

A baseball (m= 149g) approaches a bat horizontally at a speed of 40.2 m/s (90 mi/h) and is hit straight back at a speed of 45.6m/s (102mi/h). If the ball is in contact with the bat for a time of 1.10ms, what is the average force exerted on the ball by the bat ? Neglect the weight of the ball, since it is so much less than the force of the bat. Choose the direction of the incoming ball as the positive direction.

Explanation:

Use the impulse equation (a form of Newton's 2nd Law): FΔt = Δ(mv) where Δ means "change in"

The change in momentum is mBB(vf - vi) = (.150 kg)(-46.9 m/s - 40.5 m/s)

Divide this by the time interval and you get F exerted by the bat in Newtons.

Take care.

6 0
3 years ago
What is true of both gravity and magnetism?
stira [4]

Explanation:

I want to say option B - Both forces can act without objects touching.

5 0
3 years ago
The total energy of a block—spring system is 0.18 J. The amplitude is 14.0 cm and the maximum speed is 1.25 m/s. Find: (a) the m
algol13

a) The mass is 0.23 kg

b) The spring constant is 1.25 N/m

c) The frequency is 1.42 Hz

d) The speed of the block is 1.08 m/s

Explanation:

a)

We can find the mass of the block by applying the law of conservation of energy: in fact, the total mechanical energy of the system (which is sum of elastic potential energy, PE, and kinetic energy, KE) is constant:

E=PE+KE=const.

The potential energy is given by

PE=\frac{1}{2}kx^2

where k is the spring constant and x is the displacement. When the block is crossing the position of equilibrium, x = 0, so all the energy is kinetic energy:

E=KE_{max}=\frac{1}{2}mv_{max}^2 (1)

where

m is the mass of the block

v_{max}=1.25 m/s is the maximum speed

We also know that the total energy is

E=0.18 J

Re-arranging eq.(1), we can find the mass:

m=\frac{2E}{v_{max}^2}=\frac{2(0.18)}{(1.25)^2}=0.23 kg

b)

The maximum speed in a spring-mass system is also given by

v_{max} =\sqrt{\frac{k}{m}} A

where

k is the spring constant

m is the mass

A is the amplitude

Here we have:

v_{max}=1.25 m/s is the maximum speed

m = 0.23 kg is the mass

A = 14.0 cm = 0.14 m is the amplitude

Solving for k, we find the spring constant

k=\frac{v_{max}^2}{A^2}m=\frac{1.25^2}{0.14^2}(0.23)=18.3 N/m

c)

The frequency in a spring-mass system is given by

f=\frac{1}{2\pi}\sqrt{\frac{k}{m}}

where

k is the spring constant

m is the mass

In this problem, we have:

k = 18.3 N/m is the spring constant (found in part b)

m = 0.23 kg is the mass (found in part a)

Substituting and solving for f, we find the frequency of the system:

f=\frac{1}{2\pi}\sqrt{\frac{18.3}{0.23}}=1.42 Hz

d)

We can solve this part by using the law of conservation of energy; in fact, we have

E=PE+KE=\frac{1}{2}kx^2 + \frac{1}{2}mv^2

Where v is the speed of the system when the displacement is equal to x.

We know that the total energy of the system is

E = 0.18 J

Also we know that

k = 18.3 N/m is the spring constant

m = 0.23 kg is the mass

Substituting

x = 7.00 cm = 0.07 m

We can solve the equation to find the corresponding speed v:

v=\sqrt{\frac{2E-kx^2}{m}}=\sqrt{\frac{2(0.18)-(18.3)(0.07)^2}{0.23}}=1.08 m/s

#LearnwithBrainly

3 0
2 years ago
Concepto de velocidad:
Varvara68 [4.7K]

Answer:

La velocidad es una magnitud física que expresa la relación entre el espacio recorrido por un objeto, el tiempo empleado para ello y su dirección. ... Su unidad en el Sistema Internacional de Unidades es el metro por segundo (m/s), e incluye la dirección del desplazamiento

Explanation:

5 0
2 years ago
Other questions:
  • During an exothermic process, _____. during an exothermic process, _____. no heat is exchanged between the system and the surrou
    11·1 answer
  • Vector A→ has a magnitude of 8 units and makes an angle of 45° with the positive x-axis. Vector B→ also has a magnitude of 8 uni
    5·2 answers
  • How much energy is required to increase the temperature of 36.0 g of H2O from –20 °C to 50 °C, keeping in mind the following: Vi
    5·1 answer
  • 15 POINTS PLEASE PLEASE HELP ME!!
    12·1 answer
  • Why is the element carbon-14 important for paleontologist?
    14·2 answers
  • What does Newton's second law of motion describe?
    15·2 answers
  • From which evidence can a forensic expert extract DNA?
    10·1 answer
  • Two identical light bulbs, each with resistance R = 2  are connected to a source with E = 8 V and negligible internal resistanc
    10·1 answer
  • If I am lifting a box with a force of 100 N and the box has an acceleration of 10 N, what is the mass of the box?
    14·1 answer
  • The small piston of a hydraulic press has an area of 3.2 in2. If the applied force is 2.0 lb, what must the area of the large pi
    5·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!