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Usimov [2.4K]
3 years ago
11

A concrete block is pulled 7.0 m across a frictionless surface by means of a rope. The tension in the rope is 40 N; and the net

work done on the block is 247 J. What angle does the rope make with the horizontal?
Physics
1 answer:
Arturiano [62]3 years ago
5 0

Answer:

Explanation:

ΣF = ma

Also, work done is given by

W=F.d

Then, applying scalar product

W=FdCos θ

Given that W=247J, d=7m, and F=T=40N

Then,

W=FdCos θ

247=40×7Cos θ

Then,

Cos θ=0.8821

θ=arccos(0.8821 )

θ=28.1°

The angle the rope make with the horizontal is 28.1°

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Pulling up on a rope, you lift a 4.25 kg bucket of water from a well with an acceleration of 1.80 m/s2 . What is the tension in
sattari [20]

Answer:

49.3 N

Explanation:

Given that Pulling up on a rope, you lift a 4.25 kg bucket of water from a well with an acceleration of 1.80 m/s2 . What is the tension in the rope?

The weight of the bucket of water = mg.

Weight = 4.25 × 9.8

Weight = 41.65 N

The tension and the weight will be opposite in direction.

Total force = ma

T - mg = ma

Make tension T the subject of formula

T = ma + mg

T = m ( a + g )

Substitutes all the parameters into the formula

T = 4.25 ( 1.8 + 9.8 )

T = 4.25 ( 11.6 )

T = 49.3 N

Therefore, the tension in the rope is 49.3 N approximately.

8 0
3 years ago
An insulator can do which of the following? Conduct charge through it. Become positively or negatively charged. Transfer protons
ser-zykov [4K]
The correct answer is:
<span>Become positively or negatively charged

In fact, an insulator is a material where charges cannot move freely. Therefore, it can be positively or negatively charge (for example, if it is rubbed against another object, the insulator can remain with an excess of charge), but it cannot transfer charge to other objects.</span>
5 0
3 years ago
A heat engine operating between energy reservoirs at 20?c and 600?c has 30% of the maximum possible efficiency.
Anarel [89]
 <span>The maximum possible efficiency, i.e the efficiency of a Carnot engine , is give by the ratio of the absolute temperatures of hot and cold reservoir. 
η_max = 1 - (T_c/T_h) 

For this engine: 
η_max = 1 - [ (20 +273)K/(600 + 273)K ] = 0.66 = 66% 

The actual efficiency of the engine is 30%, i.e. 
η = 0.3 ∙ 0.664 = 0.20 = 20 % 

On the other hand thermal efficiency is defined as the ratio of work done to the amount of heat absorbed from hot reservoir: 
η = W/Q_h 

So the heat required from hot reservoir is: 
Q_h = W/η = 1000J / 0.20 = 5000J</span>
8 0
3 years ago
When the car was stopped by the tree, its change in velocity during the collision was-6 meters/second. This change in
HACTEHA [7]

Answer: -3 meters/second^2.

Explanation:

3 0
3 years ago
1. Determine the magnitude of two equal but opposite charges if they attract one another with a force of 0.7N when at distance o
adell [148]

Answer:

q = 2.65 10⁻⁶ C

Explanation:

For this exercise we use Coulomb's law

        F =k \frac{q_1q_2}{r^2}

In this case they indicate that the load is of equal magnitude

       q₁ = q₂ = q

the force is attractive because the signs of the charges are opposite

       F = k \ \frac{q^2}{r^2}

       q = \sqrt{\frac{F \ r^2}{k} }

we calculate

        q = \sqrt{\frac{0.7 \ 0.3^2 }{9 \ 10^9}  }

        q = \sqrt{7 \ 10^{-12} }Ra 7 10-12

        q = 2.65 10⁻⁶ C

7 0
3 years ago
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