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Ilya [14]
3 years ago
15

A 60.0-kg man jumps 1.70 m down onto a concrete walkway. His downward motion stops in 0.025 seconds. If he forgets to bend his k

nees, what force (N) is transmitted to his leg bones?
Physics
1 answer:
Zepler [3.9K]3 years ago
8 0

Answer:

The magnitude of the force transmitted to his leg bones is 1413.6 N

Explanation:

Recall that force is defined as the change in linear momentum per unit time:

F=\frac{P_f-P_i}{\Delta t}

We can use this formula to find the force transmitted to his legs. We know that the final momentum (P_f) is 0 since the person is not moving on the floor, but we need to find what the person's momentum was an instant before he touches the ground. Since we know he person's mass, all we need for the initial momentum is his velocity.

For such we use conservation of energy in free fall, knowing that he jumped from 1.7 meters:

Potential \,\,Energy \,\,at \,\,the \,\,top \,\,of \,\,the\,\, jump = U_i=m * g * h = 60*9.8*1.7 \,J\\Kinetic \,\,Energy \,\,when \,\,touching \,\,ground =KE_f= \frac{1}{2} m*v^2=\frac{60\,kg}{2} v^2\\\\KE_f=U_i\\\frac{60\,kg}{2} v^2=60*9.8*1.7 \,J\\v^2=2*9.8*1.7 \,\frac{m^2}{s^2} \\v=0.589\,\frac{m}{s}

Now with this velocity, we know the P_i (initial momentum) just before impact.

P_i=60 \,kg * 0.589 \frac{m}{s} =35.34 \,kg\,\frac{m}{s}

And since the impact lasted 0.025 seconds, we can find the force using the first formula we recalled:

F=\frac{P_f-P_i}{\Delta t}=\frac{0-35.34_i}{\0.025}: N= -1413.6\,N

so the magnitude of the force is 1413.6 N

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Researchers in the Antarctic measure the temperature to be -32°F. What is this temperature on the following scales?(a) the Celsi
Illusion [34]
Answer:

a) -35.6°C

b) 237.4 K

Explanation:

To convert temperature from degree celsius to degree fahrenheit, use the formula below:

T_c=\frac{5}{9}(T_f-32)

a) Therefore to convert -32°F to celsius, substitute it into the celsius

\begin{gathered} T_c=\frac{5}{9}(-32-32) \\  \\ T_c=\frac{5}{9}(-64) \\  \\ T_c=-35.6^0C \end{gathered}

b) To covert to the Kelvin scale, use the formula below

\begin{gathered} T_k=T_c+273 \\  \\ T_k=-35.6+273 \\  \\ T_k=237.4K \\  \end{gathered}

8 0
1 year ago
Please answer of this question​
Bogdan [553]

Answer:

\frac{\pi }{15}m

Explanation:

At 10am, the minute hand and hour hand are ' 2 hours apart', since the minute hand is at 12pm and hour hand is at 10am.

Angle between the two hands = 2/12 * 360

= 60°

Arc Length = 2\pi r(\frac{60}{360} )

= 2\pi (0.2)(\frac{1}{6} )\\= \frac{\pi }{15} m

8 0
2 years ago
12
LiRa [457]

The horizontal speed of the object 1.0 seconds later is 1) 5.0 m/s.

Explanation:

The motion of an object thrown horizontally off a cliff is a projectile motion, which follows a parabolic path that consists of two independent motions:

- A uniform motion (constant velocity) along the horizontal direction

- An accelerated motion with constant acceleration (acceleration of gravity) in the vertical direction

This means that the horizontal speed of an object in projectile motion does not change, and remains constant during the whole motion.

Since in this case the object has been launched with a horizontal speed of

v = 5.0 m/s

this means that this speed will remain constant during the motion, so its horizontal speed 1.0 s later is also 5.0 m/s.

Learn more about projectile motion:

brainly.com/question/8751410

#LearnwithBrainly

7 0
3 years ago
Plz Help me with this
AlexFokin [52]

Answer:

Cools ; size

Explanation:

The rate at which magma cools determines the size of the crystals in the new rock. Igneous rocks are formed from the cooling and solidification of molten magma which finds its way to the surface or depth of very low pressure beneath the surface. This place or depth of cooling of magma affects the cooling rate and hence the size of the crystals formed. Igneous rocks formed at depths below the surface have more time to cool and allows more time for Crystal growth and hence produce coarse grained crystal grains called Intrusive igneous rocks which have significantly larger crystals than those formed on the surface which cools rapidly and allowing very little time for crystal growth giving rise to the formation of fine grained crystals and are called extrusive igneous rocks.

6 0
3 years ago
Who think's im pretty <br> the pic is a lil hard to see
damaskus [11]

Answer:

which pic...? there is no picture attached to your question

6 0
3 years ago
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