A small rectangular block of metal must be a magnet is it

Can a goalkeeper at her/ his goal kick a soccer ball into the opponent’s goal without the ball touching the ground? The distance

PSYCHO15rus [73]

Answer:

No she cannot.

Explanation:

Let $v_h$ be the horizontal component of the ball velocity when it's kicked, assume no air resistance, this is a constant. Also let $v_v$ be the vertical component of the ball velocity, which is affected by gravity after it's kicked.

The time it takes to travel 95m accross the field is

$t = 95 / v_h$ or $v_h = 95/t$

t is also the time it takes to travel up, and the fall down to the ground, which ultimately stops the motion. So the vertical displacement after time t is 0

$s = v_vt + gt^2/2= 0$

where g = -9.8m/s2 in the opposite direction with $v_v$

$v_vt - 4.9t^2 = 0$

$v_vt = 4.9t^2$

$v_v = 4.9t$

Since the total velocity that the goal keeper can give the ball is 30m/s

$v = v_v^2 + v_h^2 = 30^2 = 900$

$(4.9t)^2 + \left(\frac{95}{t})^2 = 900$

$24.01t^2 + \frac{9025}{t^2} = 900$

Let substitute x = $t^2$ > 0

$24.01 x + \frac{9025}{x} = 900$

We can multiply both sides by x

$24.01 x^2 + 9025 = 900x$

$24.01x^2 - 900x + 9025 = 0$

$t= \frac{-b \pm \sqrt{b^2 - 4ac}}{2a}$

$t= \frac{900\pm \sqrt{(-900)^2 - 4*(24.01)*(9025)}}{2*(24.01)}$

As $(-900)^2 - 4*24.01*9025 = -56761 < 0$

The solution for this quadratic equation is indefinite

So it's not possible for the goal keeper to do this.

6 0

3 years ago

A watermelon is blown into three pieces by a large firecracker. Two pieces of equal mass m fly away perpendicular to one another

laiz [17]

Answer

given,

watermelon blown into three pieces

two pieces of mass m

both pieces speed = v = 31 m/s

mass of third piece = 3 m

using conservation of mass

$0 = m V \hat{i} + m V \hat{j} + (3\ m)V_3$

$V_3 = \dfrac{V}{3}(-\hat{i}-\hat{j})$

$V_3 = \dfrac{V}{3}\sqrt{1^2+1^2}$

$V_3 = \dfrac{V}{3}\sqrt{2}$

velocity of third component

$V_3 = \dfrac{31}{3}\sqrt{2}$

$V_3 = 14.61\ m/s$

angle

$\theta = tan^{-1}(\dfrac{-1}{-1})$

$\theta = tan^{-1}(1)$

$\theta = 45^0$

5 0

4 years ago

The graph shows a heating curve for water. Between which points on the graph would condensation occur?

Effectus [21]

Answer:

Between R and S

Explanation:

4 0

3 years ago

Peter left town A at 13:30 and travelled towards town B at an average speed of 40mph. At 13:45 Philip left town A for town B at

skad [1K]

Answer:

fbddb

Explanation:

dsbse

8 0

3 years ago

What is the change in the cell voltage when the ion concentrations in the cathode half-cell are increased by a factor of 10?

VMariaS [17]

When the ion concentrations in the cathode half-cell are increased by a factor of 10, the change in the cell voltage is ln10 times greater. This comes from the Nernst equation. Use variation to solve for the cell voltage in terms of the initial cell voltage before increasing the ion concentrations by 10.

8 0

4 years ago

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