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3 years ago

HELP ME PLZ!!! Two lifeguards pull on ropes attached to a

1 answer:

7 0

When both pull in the same direction, their net is 352.
When they pull in opposite directions, the net in one direction is 157.

If you want to set up the system of equations,
you should start with

   A + B = 352
   A - B = 157 .

then add them, etc.

You'll find that

-- Guy-A is the stronger one.
   He's the one who moves to the other side,
   and he pulls with 254.5 newtons both times.

-- Guy-B is the less strong one.
   He stays put, and pulls with 97.5 newtons.

You might be interested in

Which property of gold allows it to be used this way?

densk [106]

the electric conductivity of gold is very high

3 0

3 years ago

Final velocity will be greater than initial velocity of an object is

Natali [406]

Answer:

accelerating

Explanation:

If we consider(v > u) Acceleration:

final velocity(v)= 14m/s

initial velocity(u)=10m/s

time taken(t)= 2 seconds

a= $\frac{(v-u)}{t} =\frac{(14-10)}{2}$ =2m/s²

If we consider (v<u) Deceleration:

final velocity(v)= 3m/s

initial velocity(u)=9m/s

time taken(t)=2 seconds

a= $\frac{(v-u)}{t}=\frac{(3-9)}{2}$ = -3m/s²

4 0

2 years ago

Polonium, the Period 6 member of Group 6A(16), is a rare radioactive metal that is the only element with a crystal structure bas

Burka [1]

Answer:

Approximate atomic radius for polonium-209 is 167.5 pm .

Explanation:

Number of atom in simple cubic unit cell = Z = 1

Density of platinum = $9.232 g/cm^3$

Edge length of cubic unit cell= a = ?

Atomic mass of Po (M) = 209 g/mol

Formula used :

$\rho=\frac{Z\times M}{N_{A}\times a^{3}}$

where,

ρ = density

Z = number of atom in unit cell

M = atomic mass

$(N_{A})$ = Avogadro's number

a = edge length of unit cell

On substituting all the given values , we will get the value of 'a'.

$9.232 g/cm3=\frac{1 \times 209 g/mol}{6.022\times 10^{23} mol^{-1}\times (a)^{3}}$

$a = 3.35\times 10^{-8} cm$

Atomic radius of the polonium in unit cell = r

r = 0.5a

$r=0.5\times 3.35\times 10^{-8} cm=1.675\times 10^{-8} cm$

$1 cm = 10^{10} pm$

$1.675\times 10^{-8} cm=1.675\times 10^{-8}\times 10^{10}=167.5 pm$

Approximate atomic radius for polonium-209 is 167.5 pm.

7 0

3 years ago

Championship swimmers take about 22 s and about 30 arm strokes to move through the water in a 50 m freestyle race.The swimmer's

Tasya [4]

Answer:

4400 Joules

73.33 Joules

25.9325 Joules

Explanation:

P = Power = 800 W

t = Time = 22 s

F = Force

r = Radius of arm = 90 cm

Energy

$E=P\times t\\\Rightarrow E=800\times 22\\\Rightarrow E=17600\ J$

As the efficiency is 25%

$E=0.25\times 17600\\\Rightarrow E=4400\ J$

Energy used in the race is 4400 Joules

Half of the energy is used in the arm

$E=\frac{4400}{2}=2200\ J$

So, per stroke of paddle

$E=\frac{2200}{30}=73.33\ J$

The energy expenditure per arm stroke is 73.33 Joules

Displacement will be the half of the perimeter of the circle

$s=\frac{1}{2}\times 2\pi r\\\Rightarrow s=\frac{1}{2}\times 2\pi 0.9\\\Rightarrow s=2.82743$

Work done

$W=F\times s\\\Rightarrow F=\frac{W}{s}\\\Rightarrow F=\frac{73.33}{2.82743}\\\Rightarrow W=25.9352\ J$

The average force of the hand on the water is 25.9325 Joules

3 0

3 years ago

A satellite orbiting Earth at an orbital radius r has a velocity v. Which represents the velocity if the satellite is moved to a

satela [25.4K]

Answer:

The correct answer is V√5

Explanation:

Let V be the velocity of the satellite orbiting at radius r.

Let V(5r) be the velocity of the satellite orbiting at radius 5r.

Recall:

Escape velocity is given by:

V = √(2gr)

Where V is the escape velocity

g is the acceleration due to gravity

r is the radius of the earth.

With the above equation, we can obtain the answer to the question as follow:

V = √(2gr)

V(5r) = √(2g5r)

Next, we'll obtained the ratio of V(5r) to V as shown below

V(5r) : V => V(5r)/V

V(5r)/V = √(2g5r) / √(2gr)

V(5r)/V = √5

Cross multiply

V(5r) = V√5

From the above illustration, we can see that when the satellite is moved to 3r, then the expression for the velocity will be V√5

3 0

3 years ago