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3 years ago

A girl is whirling a ball on a string around her head in

Physics

1 answer:

Thepotemich [5.8K]3 years ago

8 0

Answer:

Answered

Explanation:

The girl whirling the ball should let go off ball when the ball is at a position such that tangent to the circle is in the direction of the target.

the tangent at any point in a circular path indicates the direction of velocity at that point. And the moment when the centripetal force is removed the ball will follow the tangential path at that moment.

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A child kicks a ball horizontally with a speed of 4.8 m/s off a deck 3.5 m off the ground. How far, in meters, from the deck doe

Vesna [10]

Answer:

2.605m

Explanation:

Using the formula for calculating Range (distance travelled in horizontal direction)

Range R = U√2H/g

U is the speed = 4.8m/s

H is the maximum height = ?

g is the acc due to gravity = 9.8m/s²

R = 3.5m

Substitute into the formula and get H

3.5 = 4.8√2H/9.8

3.5/4.8 = √2H/9.8

0.7292 = √2H/9.8

square both sides

0.7292² = 2H/9.8

2H = 0.7292² * 9.8

2H = 5.21

H = 5.21/2

H = 2.605m

Hence the height of the ball from the ground is 2.605m

7 0

3 years ago

HELP ME PLEASE URGENT WILL MARK AND 5 STARS

Artist 52 [7]

Answer:

option (B) is the correct option.

please thanks me and follow me

7 0

3 years ago

You watch a distant lady driving nails into her front porch at a regular rate of 1 stroke per second. You hear the sound of the

Igoryamba

Answer:

λ = 1360 m

Explanation:

Given data:

frequency of driving nails is given as 1 stroke per second mean at every 0.25 sec she hit the nails

speed of sound is given as 340 m/s

we know that the wave equation is given as

Speed = frequency × wavelength,

v = f × λ

where,

v = speed in meters/second (m/s)

f = frequency in Hertz (Hz)

substituing value to get wavelength of her driving nails

$340 m/s = (1Hz)\times \lambda$

$\lambda = \frac{340}{0.25}$

λ = 1360 m

4 0

3 years ago

Read 2 more answers

a sphere of diameter 6•0cm is moulded into a thin uniform wire of diameter 0•2mm.calculate the length of the wire in metres

Scilla [17]

The length of the wire is 36 m.

Explanation:

Given, Diameter of sphere = 6 cm

We know that, radius can be found by taking the half in the diameter value. So,

$\text { sphere radius, } R=\frac{D}{2}=\frac{6}{2}=3 \mathrm{cm}=3 \times 10^{-2} \mathrm{m}$

Similarly,

$\text { wire radius, } r=\frac{0.2}{2}=0.1 \mathrm{mm}=1 \times 10^{-3} \mathrm{m}$

We know the below formulas,

$\text {volume of sphere}=\frac{4}{3} \times \pi \times R^{3}$

$\text {volume of wire}=\pi \times r^{2} \times l$

When equating both the equations, we can find length of wire as below, where $\pi=\frac{22}{7}$

$\frac{4}{3} \times \pi \times R^{3}=\pi \times r^{2} \times l$

$\frac{4}{3} \times \frac{22}{7} \times\left(3 \times 10^{-2}\right)^{3}=\frac{22}{7} \times\left(1 \times 10^{-3}\right)^{2} \times l$

The $\pi$ value gets cancelled as common on both sides, we get

$\frac{4}{3} \times 27 \times 10^{-6}=10^{-6} \times l$

The $10^{-6}$ value gets cancelled as common on both sides, we get

$l=4 \times 9=36 m$

7 0

3 years ago

Consider heat transfer between two identical hot solid bodies and the air surrounding them. The first solid is being cooled by a

Nitella [24]

Answer:

The solution to the question above is explained below:

Explanation:

For which solid is the lumped system analysis more likely to be applicable?

Answer

The lumped system analysis is more likely to be applicable for the body cooled naturally.

Question :Why?

Answer

Biot number is proportional to the convection heat transfer coefficient, and it is proportional to the air velocity. When Biot no is less than 0.1 in the case of natural convection, then lumped analysis can be applied.

Further explanations:

Heat is a form of energy.

Heat transfer describes the flow of heat across the boundary of a system due to temperature differences and the subsequent temperature distribution and changes. There are three different ways the heat can transfer: conduction, convection, or radiation.

Heat transfer analysis which utilizes this idealization is known as the lumped system analysis.

The Biot number is a criterion dimensionless quantity used in heat transfer calculations which gives a direct indication of the relative importance of conduction and convection in determining the temperature history of a body being heated or cooled by convection at its surface. In heat transfer analysis, some bodies are observed to behave like a "lump" whose entire body temperature remains essentially uniform at all times during a heat transfer process.

Conduction is the transfer of energy in the form of heat or electricity from one atom to another within an object and conduction of heat occurs when molecules increase in temperature.

Convection is a transfer of heat by the movement of a fluid. Convection occurs within liquids and gases between areas of different temperature.

7 0

3 years ago