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3 years ago

A football is thrown due north across a 40 meter river and it takes 2 seconds to cover that distance.

Physics

1 answer:

Alexxx [7]3 years ago

6 0

Answer:

I. Speed = 20m/s

II. Velocity = 20m/s due North.

Explanation:

Given the following data;

Distance = 40m

Time = 2secs

To find the speed;

Mathematically, speed is given by the formula;

$Speed = \frac{distance}{time}$

Substituting into the equation, we have;

$Speed = \frac{40}{2}$

Speed = 20m/s.

In physics, we use the same formula for calculating speed and velocity. The only difference is that speed is a scalar quantity and as such has magnitude but no direction while velocity is a vector quantity and as such it has both magnitude and direction.

$Velocity = \frac{distance}{time}$

Therefore, the velocity is 20m/s due North.

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We want to construct a solenoid with a resistance of 4.30 Ω and generate a magnetic field of 3.70 × 10−2 T at its center when ap

marshall27 [118]

Answer with Explanation:

We are given that

Resistance of solenoid,R=4.3 ohm

Magnetic field,B= $3.7\times 10^{-2} T$

Current,I=4.6 A

Diameter of wire,d=0.5 mm= $0.5\times 10^{-3} m$

Radius of wire,r= $\frac{d}{2}=\frac{0.5\times 10^{-3}}{2}=0.25\times 10^{-3} m$

$1mm=10^{-3} m$

Radius of solenoid,r'=1 cm= $1\times 10^{-2} m$

$1 cm=10^{-2} m$

Resistivity of copper, $\rho=1.68\times 10^{-8}\Omega m$

We know that

$R=\frac{\rho l}{A}$

Where $A=\pi r^2$

Using the formula

$4.3=\frac{1.68\times 10^{-8}\times l}{\pi(0.25\times 10^{-3})^2}$

$l=\frac{4.3\times \pi(0.25\times 10^{-3})^2}{1.68\times 10^{-8}}=50.23 m$

Number of turns of wire= $\frac{l}{2\pi r'}$

Number of turns of wire= $\frac{50.26}{2\pi(1\times 10^{-2}}=800$

Hence, the number of turns of the solenoid,N=799

Magnetic field in solenoid,B= $\mu_0 nI$

$3.7\times 10^{-2}=4\pi\times 10^{-7} n\times 4.6$

$n=\frac{3.7\times 10^{-2}}{4\times 3.14\times 10^{-7}\times 4.6}$

$n=6404 turns/m$

$n=\frac{N}{L}$

$L=\frac{N}{n}$

$L=\frac{799}{6404}$

$L=0.125 m=0.125\times 100=12.5 cm$

Length of solenoid=12.5 cm

1m=100 cm

8 0

4 years ago

It is easier to overcome load when the load is shifted towards the wheel in a wheelbarrow why ? give reason

krok68 [10]

Answer:

The wheelbarrow's wheel and axle help the wheelbarrow to move without friction thus making it easier to push or pull. That's why it will be easier to lift a load in wheel barrow of the load is transferred towards the wheel.

4 0

3 years ago

Read 2 more answers

Which statement about polymers is true?

Mamont248 [21]

Where are the statements? You forgot to attach them lol

6 0

3 years ago

PLEASE HELP ME?!?! PLEASE PLEASE

Dmitry [639]

(1) Electric current is defined as the rate of charge flow past a given point in an electric circuit. It is measured in Coulombs/second, also called Amperes. In DC electric circuits, it can be assumed that the resistance to current flow is a constant so that the current in the circuit is related to voltage and resistance by Ohm's law, which is:

V = I*R
Where V = Voltage
I = Current
R = Resistance

(2) The answer is attached in image form down below(please find attachment)
(3) The answer is attached in image form down below(please find attachment)

(4) Renewable energy is the energy which is generated from the natural sources i.e. sun, tides, wind etc. Examples are: Solar Energy, Wind energy( windmill) etc. for electricity generation.
Advantages of Renewable Energy:
1) It is available in abundant quantity.
2) It is free to use.
3) It has low carbon emissions, therefore it is considered as green and environment friendly.
Disadvantages of Renewable Energy:
1) It is not easy to setup plants and machinery for renewable energy.
2) Initial costs for setting up those plants and machinery is quite high.
3) The energy from the natural sources is not available 24/7. In Solar energy case, energy can be used during the day time and not during night or rainy season etc.

Non-Renewable energy is energy which is taken from the sources that are available on the earth in limited quantity. Sources may be fossil fuels, natural gas, oil and coal etc.
Advantages of Non-Renewable Energy Sources:
1) They are easy to use.
2) They are cheap.

Disadvantages:
1) They will expire some day (as they are limited).
2) The speed at which such resources are being used can have serious environmental changes.
3) They release toxic gases in the air when burnt which are the major cause for global warming.
4) Since these sources are going to expire soon, prices of these sources are proliferating day by day.

Now you should judge all by yourself which is the better energy source.
-i

8 0

3 years ago

A student standing on a stationary skateboard tosses a textbook with a mass of mb = 1.35 kg to a friend standing in front of him

nataly862011 [7]

Answer:

a) $u_c=0\ m.s^{-1}$ & $m_c.v_c=m_b.v_b\times \cos\theta$

b) $v_c=0.0566\ m.s^{-1}$

c) $p_e=2.9218\ kg.m.s^{-1}$

Explanation:

Given:

mass of the book, $m_b=1.35\ kg$

combined mass of the student and the skateboard, $m_c=97\ kg$

initial velocity of the book, $v_b=4.61\ m.s^{-1}$

angle of projection of the book from the horizontal, $\theta=28^{\circ}$

velocity of the student before throwing the book:

Since the student is initially at rest and no net force acts on the student so it remains in rest according to the Newton's first law of motion.

$u_c=0\ m.s^{-1}$

where:

$u_c=$ initial velocity of the student

velocity of the student after throwing the book:

Since the student applies a force on the book while throwing it and the student standing on the skate will an elastic collision like situation on throwing the book.

$m_c.v_c=m_b.v_b\times \cos\theta$

where:

$v_c=$ final velcotiy of the student after throwing the book

$m_c.v_c=m_b.v_b\times \cos\theta$

$97\times v_c=1.35\times 4.61\cos28$

$v_c=0.0566\ m.s^{-1}$

Since there is no movement of the student in the vertical direction, so the total momentum transfer to the earth will be equal to the momentum of the book in vertical direction.

$p_e=m_b.v_b\sin\theta$

$p_e=1.35\times 4.61\times \sin28^{\circ}$

$p_e=2.9218\ kg.m.s^{-1}$

6 0

3 years ago