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Masja [62]
3 years ago
11

A soccer ball is kicked from the ground with an initial speed v at an upward angle θ. A player a distance d away in the directio

n of the kick starts running towards the ball at that instant. What must be his average speed if he is to meet the ball just before it hits the ground?
Physics
1 answer:
LuckyWell [14K]3 years ago
3 0

Answer:

U = √Rg/sin2θ

Explanation:

Using the formula for "range" in projectile motion to derive the average speed before the ball hits the ground.

Range is the distance covered by the body in the horizontal direction from the point of launch to the point of landing.

According to the range formula,

R = U²sin2θ/g

Cross multiplying we have;

Rg = U²sin2θ

Dividing both sides by sin2θ, we have;

U² = Rg/sin2θ

Taking the square root of both sides we have;

√U² = √Rg/sin2θ

U = √Rg/sin2θ

Therefore, his average speed if he is to meet the ball just before it hits the ground is √Rg/sin2θ

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What can one say for sure about element #99, Einsteinium (Es))? a) There's no such element! b) It is an alkali metal. c) It is r
Dmitrij [34]

Answer:

Option (C)

Explanation:

Einsteinium is an element of the periodic table grouped in the Actinide series, with atomic number 99. They are dense element and highly electro-positive. <u>They are highly radioactive</u>, i.e the atoms within the element are unstable and constantly decay until they reach a stable environment. It has 99 number of electrons and protons, 153 number of neutrons.

Due to its high radioactivity, they are health hazardous and can used in making nuclear weapons but their uses are very limited and unknown.

Thus, the correct answer is option (C).

8 0
4 years ago
How might viral diseases be prevented?
Sindrei [870]

Answer:

There are antiviral medicines to treat some viral infections. Vaccines can help prevent you from getting many viral diseases.

3 0
3 years ago
A current of 9 A flows through an electric device with a resistance of 43 Ω. What must be the applied voltage in this particular
NeTakaya
Answer:
387 volts

Explanation:
Ohm's law is used to relate voltage, current and resistance.
The formula is as follows:V = I * R
where:
V is the applied voltage (measured in volts)
I is the current flowing (measured in amperes)
R is the resistance (measured in ohm)

In the given, we have:
current (I) = 9 amperes
resistance (R) = 43 ohm

Substitute with the givens in the above formula to get the voltage as follows:
V = 9 * 43
V = 387 volts

Hope this helps :)
4 0
3 years ago
Read 2 more answers
19. A mass of gas has a volume of 4 m3, a temperature of 290 K, and an absolute pressure of 475 kPa. When the gas is allowed to
Aleks [24]

Recall this gas law:

\frac{P₁V₁}{T₁} = \frac{P₂V}{T₂}

P₁ and P₂ are the initial and final pressures.

V₁ and V₂ are the initial and final volumes.

T₁ and T₂ are the initial and final temperatures.

Given values:

P₁ = 475kPa

V₁ = 4m³, V₂ = 6.5m³

T₁ = 290K, T₂ = 277K

Substitute the terms in the equation with the given values and solve for Pf:

\frac{475*4}{290} = \frac{P₂*6.5}{277}

<h3>P₂ = 279.2kPa</h3>
8 0
3 years ago
A skater slides across the ice with an initial velocity of 5.0 m/s. She slows 10 points
zvonat [6]

Explanation:

Given that,

The initial velocity of a skater is, u = 5 m/s

She slows to a velocity of 2 m/s over a distance of 20 m.

We can find the acceleration of skater. It is equal to the rate of change of velocity. So, it can be calculated using third equation of motion as follows :

v^2-u^2=2as

a = acceleration

a=\dfrac{v^2-u^2}{2s}\\\\a=\dfrac{(2)^2-(5)^2}{2\times 20}\\\\a=-0.525\ m/s^2

So, her acceleration is 0.525\ m/s^2 and she is deaccelerating. Also, her initial velocity is given i.e. 5 m/s.

7 0
3 years ago
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