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vitfil [10]
3 years ago
10

An athlete is working out in the weight room. He steadily holds 50 kilograms above his head for 10 seconds. Which statement is t

rue about this situation?
A.
The athlete isn’t doing any work because he doesn’t move the weight.
B.
The athlete isn’t doing any work because he doesn’t hold the weight long enough.
C.
The athlete is doing work because he prevents the weight from falling downward.
D.
The athlete is doing work because 50 kilograms is a significant load to lift.
Physics
1 answer:
postnew [5]3 years ago
3 0

Answer:

A. The athlete isn’t doing any work because he doesn’t move the weight.

Explanation:

We must remember the definition of work, which says that work is equal to the product of mass by the distance displaced. In this case, the athlete only does work when he lifts the weight from the ground to the point where he holds the weight suspended.

So when he's holding the weight, he doesn't do any work.

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Steam at 100°C is condensed into a 38.0 g aluminum calorimeter cup containing 280 g of water at 25.0°C. Determine the amount of
KonstantinChe [14]

Answer:

7.2g

Explanation:

From the expression of latent heat of steam, we have

Heat supplied by steam = Heat gain water + Heat gain by calorimeter

mathematically,

m_{s}c_{w} \alpha _{w} + m_{s}l=m_{w}c_{w} \alpha _{w} +m_{c}c_{c} \alpha c_{c}

L=specific latent heat of water(steam)=2268J/g

c_{w}=specific heat capacity=4.2J/gK

c_{c}=specific heat capacity of calorimeter =0.9J/gk

m_{w}=280g

m_{c}=38g

α=change in temperature

\alpha _{c}=(40-25)=15

\alpha _{w}=(40-25)=15

\alpha _{s}=(100-40)=60

Note: the temperature of the calorimeter is the temperature of it content.

From the equation, we can make m_{s} the subject of formula

m_{s}=\frac{m_{w}c_{w} \alpha +m_{c}c_{c}\alpha}{c_{w}\alpha +l}

Hence

m_{s}=\frac{(280*4.2*15) +(38*0.9*15)}{(4.2*60) +2268} \\m_{s}=\frac{18153}{2520}\\ m_{s}=7.2g

Hence the amount of steam needed is 7.2g

6 0
3 years ago
1. Which of the following states would likely get hit by both hurricanes and tornadoes? (Points : 1)
bogdanovich [222]
I would have to say Texas because, obviously, its on the coast, and because I know for a fact Oklahoma is VERY prone to Tornadoes and I also know Dallas (and surrounding areas) has a few tornadoes a year:)

I hope I helped:)
  
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5 0
3 years ago
Read 2 more answers
Rahul has 2 bulbs connected across two cells in a simple circuits shown. How can he make the bulbs glow dimmer?
Ray Of Light [21]

Answer:

in the parallel connection the light bulbs shine less than in the series connection

Explanation:

In a series circuit the current through the whole circuit is the same, therefore the power (brightness) of each bulb is

           P = i² R

where R is the resistance of each bulb and i the current of the circuit.

If we connect the light bulbs and the cells in parallel, the current in the circuit is the sum of the east that passes through each light bulb,

            i = i₁ + i₂

if the two light bulbs are the same

           i = 2 i₁

           i₁ = i / 2

so the power of each bulb is is

           P = i₁² R

           P = R i² / 4

           P = ¼ P_initial

Therefore we see that in the parallel connection the light bulbs shine less than in the series connection

3 0
3 years ago
A car’s tire rotates 5.25 times in 3 seconds. What is the tangential velocity of the tire?
Lena [83]

The tangential velocity of the car's tire is the product of the angular velocity and radius of the car's tire which is 11(r) m/s.

<h3>Angular velocity of the tire</h3>

The angular velocity of the tire is the rate of change of angular displacement of the tire with time.

The magnitude of the angular velocity of the tire is calculated as follows;

ω = 2πN

where;

  • N is the number of revolutions per second

ω = 2π x (5.25 / 3)

ω =  11 rad/s

<h3>Tangential velocity of the tire</h3>

The tangential velocity of the car's tire is the product of the angular velocity and radius of the car's tire.

The magnitude of the tangential velocity is caculated as follows;

v = ωr

where;

  • r is the radius of the car's tire

v = 11r m/s

Learn more about tangential velocity here: brainly.com/question/25780931

4 0
2 years ago
4. A student measures a temperature several times. The readings lie between 29.6 and 30.2 K. This
Alona [7]

Answer:

(C) apparently written incorrectly - it should be 29.9 +- .3 K

(read 29.9 plus or minus .3 K)

8 0
3 years ago
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