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kvasek [131]
2 years ago
9

When you jump from an elevated position you usually bend your knees upon reaching the ground. By doing this, you make the time o

f the impact about 10 times as great as for a stiff-legged landing. In this way the average force your body experiences is ________.a. less than 1/10 as great. b. more than 1/10 as great. c. about 1/10 as great.d. about 10 times as great.
Physics
1 answer:
dsp732 years ago
7 0

Answer:

c. about 1/10 as great.

Explanation:

While jumping form a certain height when we bend our knees upon reaching  the ground such that the time taken to come to complete rest is increased by 10 times then the impact force gets reduced to one-tenth of the initial value when we would not do so.

This is in accordance with the Newton's second law of motion which states that the rate of change in velocity is directly proportional to the force applied on the body.

Mathematically:

F\propto\frac{d}{dt} (p)

\Rightarrow F=\frac{d}{dt} (m.v)

since mass is constant

F=m\frac{d}{dt}v

when dt=10t

then,

F'=m.\frac{v}{10\times t}

F'=\frac{1}{10} \times \frac{m.v}{t}

F'=\frac{F}{10} the body will experience the tenth part of the maximum force.

where:

\frac{d}{dt} = represents the rate of change in dependent quantity with respect to time

p= momentum

m= mass of the person jumping

v= velocity of the body while hitting the ground.

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Answer:

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2 years ago
4. Shirley Bored sits in her seat in the English classroom. The force of gravity on Earth pulls
Sedbober [7]

Answer:

600 N upward

Explanation:

According to Newton's third law, for every action their is an equal and opposite reaction. The equal and opposite reaction to a downward force of magnitude 600 N is an upward force of magnitude 600 N

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2 years ago
Two wooden crates rest on top of one another. The smaller top crate has a mass of m1 = 25 kg and the larger bottom crate has a m
faust18 [17]

Answer:

Explanation:

Let the bigger crate be in touch with the ground which is friction less. In the first case both m₁ and m₂ will move with common acceleration because m₁ is not sliding over m₂.

1 ) Common acceleration a = force / total mass

= 234 / ( 25 +91 )

= 2.017 m s⁻².

2 ) Force on m₁ accelerating it , which is nothing but friction force on it by m₂

= mass x acceleration

= 25 x 2.017

= 50.425 N

The same force will be applied by m₁ on m₂ as friction force which will act in opposite direction.

3 ) Maximum friction force that is possible between m₁ and m₂

= μ_s m₁g

= .79 x 25 x 9.8

= 193.55 N

Acceleration of m₁

= 193 .55 / 25

= 7.742 m s⁻²

This is the common acceleration in case of maximum tension required

So tension in rope

= ( 25 +91 ) x 7.742

= 898 N

4 ) In case of upper crate sliding on m₂ , maximum friction force on m₁

=  μ_k m₁g

= .62 x 25 x 9.8

= 151.9 N

Acceleration of m₁

= 151.9 / 25

= 6.076 m s⁻².

6 0
2 years ago
When energy is transferred to air, what happens to the particles of air? (1 point) They move slower. They move faster. They cool
zubka84 [21]
This question is a critical question. as we all know, when energy is added to any state of water, the particles move faster. and when energy is taken away from any state of water, the particles reduce speed. same with the particles of air. when energy is added; they move faster. when energy is removed; they move slower. so the answer is they move faster
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3 years ago
Read 2 more answers
An electric light is plugged into a 120-V outlet. If the current in the bulb is 0.50 A, how much electrical energy does the bulb
ioda

Answer:

= 54,000 Joules or 54 kJ

Explanation:

Electrical energy is given by the formula;

E = VIt; where V is the potential difference in volts, I is the current and t is the time in seconds.

Therefore;

Electrical energy = 120 V × 0.50 A × 15 ×60 seconds

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Thus; the electrical energy is 54,000 joules or 54 kJ

7 0
2 years ago
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