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Sergio [31]
3 years ago
14

April does 1800 J of work to get a canoe moving from rest. April and the canoe have a mass of 70 kg. a. What is the kinetic ener

gy of April and the canoe after she does the work?
Physics
2 answers:
Katyanochek1 [597]3 years ago
5 0

E = (1/2)mv²

1800 = (1/2)(70)v²

Solving for v²

1800(2)/70 = v²

v² = 55.714

√v² = √55.714

v = ~7.46 m/s

Alex_Xolod [135]3 years ago
4 0

Answer:

Kinetic energy = 1800 J

Explanation:

As per work energy theorem we know that the total work done on the system is always equal to the change in kinetic energy of the system

So we can say it as

W_{net} = KE_f - KE_i

here we can say that initially it starts from the rest state so the initial kinetic energy is given as

KE_i = 0

now from above equation we can say

W_{net} = KE_f - 0

so final kinetic energy must be equal to net work done on it

kinetic energy = 1800 J

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A baseball leaves a bat with a horizontal velocity of 20 m/s. In a time of 0.25 s, How far will it have traveled horizontally?
Maurinko [17]

Distance traveled by the ball is given by

distance = speed \times time

here we know that

speed = 20 m/s

times = 0.25 s

now we have

distance = 20 \times 0.25

distance = 5 m

so ball will travel 5 m distance in the given interval of time

6 0
3 years ago
What is the direction of the force for a negative charge moving downward in a magnetic field pointing to the left?
velikii [3]

Answer: A

Out of the screen

Explanation:

Using right hand rule, the magnetic force is perpendicular to the plane form by the magnetic field of a charged particle and its speed. Which will be into the screen.

But the negative charged particle moves in the opposite direction of the positive charged particle. Therefore, the magnetic force direction will be out of the screen

5 0
3 years ago
A fireboat is to fight fires at coastal areas by drawing seawater with a density of 1030 kg/m3 through a 10-cm-diameter pipe at
GaryK [48]

Answer:

50.93 m/s

199.5 kW

Explanation:

From the question, the nozzle exit diameter = 5 cm, Radius= diameter/2= 5cm/2= 2.5cm. we can convert it to metre for unit consistency= (2.5×0.01)=

0.025m

We can calculate the The cross sectional area of the nozzle as

A= πr^2

A= π ×0.025^2

= 1.9635 ×10^- ³ m²

From the question, the water is moving through the pipe at a rate of 0.1 m /s , then for the water to move through it at a seconds, it must move at

(0.1 / 1.9635 ×10^- ³ m²)

= 50.93 m/s

During the Operation of the pump, the Dynamic energy of the water= potential energy provided there is no loss during the Operation

mgh = 1/2mv²

We can make "h" subject of the formula, which is the height of required head of water

h = (1/2mv²)/mg

h= v² / 2g

h = 50.93² / (2 ×9.81)

h = 132.21m

From the question;

The total irreversible head loss of the system = 3 m,

the given position of nozzle = 3 m

the total head the pump needed=(The total irreversible head loss of the system + the position of the nozzle + required head of water )

=(3 + 3 + 132.21m)

=138.21m

mass of water pumped in a seconds can be calculated since we know that mass is a product of volume and density

Volume= 0.1m³

Density of sea water=1030 kg/m

(0.1 m^3× 1030)

= 103kg

We can calculate the Potential enegry, which is = mgh

= (103 ×9.81 × 138.21)

= 139651.5 Watts

= 139.65kW

To determine required shaft power input to the pump and the water discharge velocity

Energy= efficiency × power

But we are given efficiency of 70 percent, then

139651.5 Watts = 0.7P

=199502.18 Watts

P=199.5 kW

Therefore, the required shaft power input to the pump and the water discharge velocity is 199.5 kW

5 0
2 years ago
Two in-phase loudspeakers that emit sound with the same frequency are placed along a wall and are separated by a distance of 5.0
e-lub [12.9K]

Answer:

f = 421.8 Hz

Explanation:

When she moved a distance of 1 m from mid point she observe first destructive interference due to two speakers

so we can say that path difference of sound due to two speakers will be equal to half of the wavelength

so path difference is given as

\Delta L = {3.5^2 + 12^2}^{0.5} - {1.5^2 + 12^2}^{0.5}

so it will be

\Delta L = 12.5 - 12.093

\Delta L = 0.4066

now we know that

\frac{\lambda}{2} = 0.4066

\lambda = 0.813

now frequency of sound is given as

f = \frac{v}{\lambda}

f = \frac{343}{0.813}

f = 421.8 Hz

4 0
3 years ago
Electrical power companies sell electrical energy
mixer [17]

Heat used by electric heater :

Q = m • c • ∆T

Q = (75 kg)(4200 J/kg°C)(43°C - 15°C)

Q = 8.82 × 10⁶ J

Cost of electrical energy :

Cost = (8.82 × 10⁶ J)/(3.6 × 10⁶ J) • ($ 0.15)

Cost = $ 0.3675

4 0
2 years ago
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