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statuscvo [17]
3 years ago
8

A book rests on the shelf of a bookcase. The reaction force to the force of gravity acting on the book is 1. The force of the sh

elf holding the book up. 2. The force exerted by the book on the earth. 3. The weight of the book. 4. The frictional force between book and shelf. 5. None of these.
Physics
2 answers:
Stells [14]3 years ago
8 0

Answer: the force exerted by the book on the earth

Hoochie [10]3 years ago
6 0

Answer:

1. The force of the shelf holding the book up.

Explanation:

The free body diagram of the book is as follows:

1 - The weight of the book towards downwards

2 - The normal force that the shelf exerts on the book towards upwards.

Since the book is at rest, these two forces are equal to each other and according to Newton's Third Law the reaction force to the force of gravity is equal but opposite to the weight of the book. This reaction force is the one that holds the book up on the shelf.

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Suppose that the separation between two speakers A and B is 4.80 m and the speakers are vibrating in-phase. They are playing ide
Hatshy [7]

Answer:

X=8.44m

Explanation:

From the question we are told that

Distance b/w A&B x=4.80m

Frequency f=134Hz

Sound speed v=343m/s

Generally the equation for wavelength is mathematically given as

\lambda=v/f

\lambda/2=1/2*v/f

\lambda/2=1/2*\frac{343}{135}

\lambda/2=1.27037037

Generally the destructive interference X is mathematically given by

\sqrt{4.8^2 +X^2} -X=1.27037037\\

23.04+BC^2=X^2+1.613+2.54*X

Therefore the destructive interference is

X=8.44m

4 0
3 years ago
Someone help please i need to finish this
Tom [10]

Answer:

4th answer

Explanation:

The gradient of a distance-time graph gives the speed.

gradient = distance / time = speed

Here, the gradient is a constant till 30s. So it has travelled at a constant speed. It means it had not accelarated till 30s. and has stopped moving at 30s.

6 0
2 years ago
A bird takes off from the tree and after 5 s is flying at a speed of 10 m/s. Calculate
Volgvan

Answer:

10miles/second

Explanation:

Change in velocity of the bird is expressed as the difference between the final velocity and initial velocity of the body.

Change in velocity = Final velocity - initial velocity

Since the bird takes off from the tree, the initial velocity of the bird = 0miles/sec

Final velocity = 10miles/secs

Change in velocity = 10-0

Change in velocity = 10miles/second

6 0
2 years ago
The amount of gas that a helicopter uses is directly proportional to the number of hours spent flying. the helicopter flies for
igomit [66]

Answer:

The helicopter uses 35 gallons to fly for 5 hours.

Explanation:

The amount of gas that a helicopter uses for flying varies directly proportional to the number of hours spent flying.

g ∝ T

where g represents amount of gas and T time of flight.

Then,

\therefore \frac{g_1}{g_2}=\frac{T_1}{T_2}

The helicopter files 4 hours and uses 28 gallons of fuel.

Here, g₁= 28 gallons, T₁=4 hours

g₂=?, T₂=5 hours.

\therefore \frac{g_1}{g_2}=\frac{T_1}{T_2}

\Rightarrow \frac{28}{g_2}=\frac{4}{5}

⇒28×5= g₂×4

⇒ g₂×4=28×5

\Rightarrow g_2=\frac{28\times 5}{4}

\Rightarrow g_2=35 gallons

The helicopter uses 35 gallons to fly for 5 hours.

5 0
3 years ago
For the long life cells we have to connect them in ____ combination​
NISA [10]

Answer:

Parallel combination.

5 0
3 years ago
Read 2 more answers
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