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3 years ago

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An arrow is shot vertically downwards, and strikes the ground at a speed of 29.2 m/s, 10.9 m below from where it was shot. With

what initial speed was the arrow shot?

1 answer:

ella [17]3 years ago

5 0

Answer:

Explanation:

Ignoring air resistance

v² = u² + 2as

u = √(v² - 2as)

u = √(29.2² - 2(9.81)(10.9))

u = 25.27413... 25.3 m/s

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exis [7]

Answer:

She can swing 1.0 m high.

Explanation:

Hi there!

The mechanical energy of Jane (ME) can be calculated by adding her gravitational potential (PE) plus her kinetic energy (KE).

The kinetic energy is calculated as follows:

KE = 1/2 · m · v²

And the potential energy:

PE = m · g · h

Where:

m = mass of Jane.

v = velocity.

g = acceleration due to gravity (9.8 m/s²).

h = height.

Then:

ME = KE + PE

Initially, Jane is running on the surface on which we assume that the gravitational potential energy of Jane is zero (the height is zero). Then:

ME = KE + PE (PE = 0)

ME = KE

ME = 1/2 · m · (4.5 m/s)²

ME = m · 10.125 m²/s²

When Jane reaches the maximum height, its velocity is zero (all the kinetic energy was converted into potential energy). Then, the mechanical energy will be:

ME = KE + PE (KE = 0)

ME = PE

ME = m · 9.8 m/s² · h

Then, equallizing both expressions of ME and solving for h:

m · 10.125 m²/s² = m · 9.8 m/s² · h

10.125 m²/s² / 9.8 m/s² = h

h = 1.0 m

She can swing 1.0 m high (if we neglect dissipative forces such as air resistance).

6 0

3 years ago

Please help me with this question

snow_lady [41]

politics. Famous possible eg is of Werner Heisenberg in WW2. He delayed German attempt to build a nuclear bomb. US did build one ... hiroshima and nagasaki.

debbie may have got skilfully lucky by trial and error

6 0

3 years ago

Read 2 more answers

Plaskett's binary system consists of two stars that revolve in a circular orbit about a center of mass midway between them. This

vova2212 [387]

Answer:

$1.554\times 10^{32}\ \text{kg}$

Explanation:

M = Mass of each star

T = Time period = 15.5 days

v = Orbital velocity = 230 km/s

G = Gravitational constant = $6.674\times 10^{-11}\ \text{Nm}^2/\text{kg}^2$

Radius of orbit is given by

$R=\dfrac{vT}{2\pi}$

We have the relation

$\dfrac{Mv^2}{R}=\dfrac{GM^2}{(2R)^2}\\\Rightarrow M=\dfrac{4Rv^2}{G}\\\Rightarrow M=\dfrac{4\dfrac{vT}{2\pi}v^2}{G}\\\Rightarrow M=\dfrac{2v^3T}{\pi G}\\\Rightarrow M=\dfrac{2\times 230000^3\times 15.5\times 24\times 60\times 60}{\pi\times 6.674\times 10^{-11}}\\\Rightarrow M=1.554\times 10^{32}\ \text{kg}$

The mass of each star is $1.554\times 10^{32}\ \text{kg}$

6 0

3 years ago

A homeowner uses a snowblower to clear his driveway. knowing that the snow is discharged at an average angle of 40° with the hor

Nesterboy [21]

given that snow is projected at an angle of 40 degree

It range is given as a = 19 ft

$a = 19 * 0.3048 = 5.8 m$

now we can use the formula of horizontal range

$R = \frac{v_o^2 sin2\theta}{g}$

$5.8 =\frac{ v_o^2 sin(2*40)}{9.8}$

$5.8 = \frac{v_o^2 * sin80}{9.8}$

$v_o^2 = 57.7$

$v_o = 7.6 m/s$

<u>so its initial speed must be 7.6 m/s</u>

8 0

3 years ago

If you double the net force on an object what is the result on the acceleration?

melamori03 [73]

Answer:the acceleration will double

Explanation:

3 0

3 years ago