Are sharks endangered from natural selection or artificial selection or both?

A football punter wants to kick the ball so that it is in the air for 4.2 s and lands 55 m from where it was kicked. Assume that

earnstyle [38]

Answer:

$57.24^{\circ}$

24.21 m/s

Explanation:

x = Displacement in x direction = 55 m

y = Displacement in x direction = 0

$y_0$ = Height of the ball when the ball is kicked = 1 m

t = Time taken = 4.2 s

$a_y=g$ = Acceleration due to gravity = $-9.81\ \text{m/s}^2$

u = Initial velocity of ball

Displacement in x direction is given by

$x=u_xt+\dfrac{1}{2}a_xt^2\\\Rightarrow 55=4.2u_x+0\\\Rightarrow u_x=\dfrac{55}{4.2}\\\Rightarrow u\cos\theta=13.1\ \text{m/s}\\\Rightarrow u=\dfrac{13.1}{\cos\theta}$

Displacement in y direction is given by

$y=y_0+u_yt+\dfrac{1}{2}a_yt^2\\\Rightarrow 0=1+4.2u\sin\theta+\dfrac{1}{2}\times (-9.81)\times 4.2^2\\\Rightarrow 0=4.2u\sin\theta-85.5242\\\Rightarrow u\sin\theta=20.36\ \text{m/s}\\\Rightarrow u=\dfrac{20.36}{\sin\theta}$

$\dfrac{13.1}{\cos\theta}=\dfrac{20.36}{\sin\theta}\\\Rightarrow \dfrac{20.36}{13.1}=\dfrac{\sin\theta}{\cos\theta}\\\Rightarrow \theta=\tan^{-1}\dfrac{20.36}{13.1}\\\Rightarrow \theta=57.24^{\circ}$

The ball should be kicked at an angle of $57.24^{\circ}$

$u=\dfrac{13.1}{\cos\theta}=\dfrac{13.1}{\cos57.24^{\circ}}\\\Rightarrow u=24.21\ \text{m/s}$

The initial speed of the ball is 24.21 m/s.

3 0

3 years ago

A student investigated how length affects resistance of a wire.

Mrac [35]

Answer:

X is ammeter and Y is voltmeter

Explanation:

The resistance of a wire is directly proportional to the length of the wire. That is the longer the length of the wire, the higher the resistance and the shorter the length of the wire, the smaller the resistance.

Ammeter is a measuring instrument used to measure the current in a circuit by connecting the meter in series with the circuit.

Ammeter is a measuring instrument used to measure the potential difference between two points by connecting the meter in parallel to the points.

Meter X is an ammeter since it is connected in series and meter Y is a voltmeter because it is connected in parallel.

4 0

3 years ago

Please help meeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeeee

Charra [1.4K]

Answer:

try finding on a website

Explanation:

6 0

3 years ago

Why can we never prove that a hypothesis is true?

erma4kov [3.2K]

A theorem can be proven (from axioms or prior theorems), using logic.

A hypothesis can be supported by evidence. The more evidence in support of the hypothesis, the more likely the hypothesis is to be correct. However, you’re always at the mercy of contrary evidence appearing in the future, to reduce the likelihood or even invalidate a hypothesis.

A (mathematical) proof suffers no such vulnerability to future evidence, as long as you hold the axioms of the theory to be true, and as long as there was no flaw in the construction of the proof.

7 0

3 years ago

Which object had more potential energy when it was lifted to a distance of 1000 centimeters? Show your calculation.

RSB [31]

Explanation:

We Know That

POTENTIAL ENERGY= MASS*g*HEIGHT

When the objects are lifted to same height then the object with heavier mass would have the highest potential energy

.

5 0

2 years ago