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mihalych1998 [28]
2 years ago
7

What is the average speed of an athlete who runs 1500m in 4 minuts?

Physics
1 answer:
krek1111 [17]2 years ago
3 0

Answer: 6.25 meters/second

Explanation:

First convert 4 minutes to the standard SI unit of time (seconds)

      4 min * (60 sec/1 min) = 250 seconds

Next recognize that average speed is found by dividing total distance (d) by time (t).

       average speed = d/t

Substitute in known values and solve

       average speed = 1500 m/250 sec = 6.25 meters/sec

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A 0.5 kg ball is dropped from rest at a point 1.2m above the floor. The ball rebounds straight upward to a height of 0.7m. What
Yuki888 [10]

Answer:

4.281 kgm/s upward

Explanation:

Impulse:This can be defined product of force and time. The S.I unit of impulse is Ns.

From Newton's second law of motion,

Impulse = Change in momentum.

I = mΔv....................... Equation 1.

Where m = mass of the ball, Δv = change in velocity of the ball  

and Δv = v -u

Where u = velocity of the ball before it hit the floor, v = velocity of the ball after if hit the floor

I = m(v-u) -------------- Equation 2

But

the initial kinetic energy of the ball = potential energy at the initial height (1.2 m above)

1/2mu² = mgh₁

Where h₁ = initial height. or height of the ball before collision

making u the subject of the equation,

u = √(2gh₁)........................ Equation 3

Where h₁ = 1.2 m g = 9.81 m/s²

Substitute into equation 3

u = √(2×1.2×9.81)

u =√(23.544)

u = -4.852 m/s.

Note: u is negative because the ball was moving downward at the first instance.

Similarly,

v = √(2gh₂)............................. Equation 3

h₂ = height of the ball after collision

Given: h₂ = 0.7 m, g = 9.81 m/s²

Substitute into equation

v = √(2×9.81×0.7)

v = √13.734

v = 3.71 m/s.

Also given: m = 0.5 kg,

Substituting into equation 2

I = 0.5(3.71-(4.852)

I = 0.5(8.562)

I = 4.281 kgm/s. Upward.

Thus the impulse = 4.281 kgm/s upward

7 0
4 years ago
Before going in for an annual physical, a 70.0-{\rm kg} person whose body temperature is 37.0{\rm ^{\circ} C} consumes an entire
Grace [21]

Answer:

A) The person's body temperature T_final after equilibrium is attained = 36.85°C

B) The change in the person's temperature after equilibrium is attained = 0.15°C

A high-quality medical thermometer can measure temperature changes as small as 0.1°C, hence, YES, it would detect the minute drop by 0.15°C too.

Explanation:

If we assume that the soft drink has the same density as water (since it is stated in the question that it is mostly water).

Density of water = 1 g/mL = 1 kg/L

Ignoring any heating by the person's metabolism,

A) So, heat lost by the human body = heat gained by the soft drink as it attains thermal equilibrium with the human body

Let the final temperature of the human body + soft drink set up be T

Heat lost by the human body = mCΔT

m = mass of the human body = 70.0 kg

C = Specific heat capacity of the human body = 3480 J/kg.K

ΔT = Temperature change of the human body = 37 - (Final temperature) = 37 - T

Heat lost by the body = 70 × 3480 × (37 - T)

= (9,013,200 - 243,600T) J

Heat gained by soft drink = mCΔT

m = mass of the soft drink = density × volume = 1 × 0.355 = 0.355 kg

C = specific heat capacity of the soft drink = specific heat capacity of the soft drink = 4182 J/kg.K

ΔT = (final temperature) - 12 = (T - 12)

Heat gained by the soft drink = 0.355 × 4182 × (T - 12) = (1,484.61T - 17,815.32) J

heat lost by the human body = heat gained by the soft drink as it attains thermal equilibrium with the human body

(9,013,200 - 243,600T) = (1,484.61T - 17,815.32)

9,013,200 + 17,815.32 = 1,484.61T + 243,600T

9,031,015.32 = 245,084.61T

T = (9,031,015.32/245,084.61)

= 36.8485614825 = 36.85°C

B) The change in the person's temperature = 37 - 36.85 = 0.15°C

A high-quality medical thermometer can measure temperature changes as small as 0.1°C, hence it would detect the minute drop by 0.15°C too.

Hope this Helps!!!

5 0
4 years ago
Hello, I need help. Due right now
ryzh [129]

Answer: See below

Explanation:

\\ \mathrm{Given:} \\\mathrm{Mass \ of \ first \ car}$\left(m_{1}\right)=1383 \mathrm{~kg}$ \\ Velocity $\left(\overrightarrow{V_{1}}\right)=-11.2\ {\math} \mathrm{m} / \mathrm{s}$\\ Mass of second car -$\left(m_{2}\right)=1732 \mathrm{~kg}$\\ Velocity $\left(\vec{v}_{2}\right)=31.3 {\math} \mathrm{m} / \mathrm{s}$

m_{1} \vec{v}_{1}+m_{2} \vec{v}_{2}=\left(m_{1}+m_{2}\right) \vec{v} \\1383(-11.2 {\math})+1732(31.3 {\math}) \\=(1383+1732) \vec{v} \\-15489.6 {\math}+54211.6 {\math}=3115 \vec{v} \\ \vec{v}=(17.4 {\math}-4.972 {\math}) \ \mathrm{m/s}

\text { So magnitude } \vec{|v|} =\sqrt{(17.4)^{2}+(-4.972)^{2}} \\ =\sqrt{327.605} \\ =18.099 \mathrm \ {m/s} \\

\text { Direction } \\\theta=\tan ^{-1}\left(\frac{-4.972}{17.4}\right) \\\theta=-15.945^{\circ}\end{gathered}

Therefore, both cars move with a velocity of 18.099 m/s in the direction of 15.945° downward from the x-axis (east)

7 0
3 years ago
Read 2 more answers
Equal masses are suspended from two separate wires made of the same material. The wires have identical lengths. The first wire h
choli [55]
D. I think is the correct answer
6 0
3 years ago
Use the dropdown menus to complete the paragraph about how the troposphere is heated.
Korvikt [17]

Answer:

Radiation

Conduction

Convection

Current

Explanation:Trust me just took the test also can i get brainliest please

4 0
4 years ago
Read 2 more answers
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