Ready-mix concrete can typically remain in the mixer for up to two hours before it starts to set and harden, making it difficult or impossible to use. Correct choice is option c.
The setting and hardening of concrete is a chemical process that occurs when water is added to the dry mix of cement, sand, and aggregates. Once the mixing process starts, a chemical reaction begins that produces heat, causing the concrete to start setting and hardening.
In general, ready-mix concrete should be used as soon as possible after mixing to ensure that it retains its workability and strength. If the concrete remains in the mixer for too long, it may start to set and harden, making it difficult or impossible to use. Option c is correct answer.
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What kind of forces cause an object to accelerate? *
O balanced forces
Ofrictional forces
Ounbalanced forces
O gravitational forces
The kind of force that significantly cause an object to accelerate is known as unbalanced force. Thus, the correct option for this question is C.
What is Force?Force may be defined as a type of physical characteristic that stimulates the pushing and pulling of an object. It is significantly caused by the interaction of one object with respect to another. It is a vector quantity and it has both magnitude and direction.
According to the famous scientist, Newton, an object will only accelerate if it possesses a net or unbalanced force. The presence of an unbalanced force will definitely produce an object to move in a specific direction. According to him, acceleration changes its speed, its direction, or both its speed and direction.
Therefore, the kind of force that significantly cause an object to accelerate is known as unbalanced force. Thus, the correct option for this question is C.
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one afternoon, huyen and phong go outside after it stops raining. the sun comes out, and when they look up, they can see a rainbow. huyen knows that the different colors of light in the rainbow come from waves that have different wavelengths. if each color has a different wavelength, why are huyen and phong able to see all of the different colors at the same time?
Answer: The light waves result in colors that blend together
A construction worker uses ab board and log as a lever to lift a heavy rock. He applies a force of 27.5 N without use of a lever, however with the use of the lever, he applies a force of 10.0 N. What is the mechanical advantage
The mechanical advantage of the lever is approximately 0.364
To calculate the mechanical advantage (MA) of the lever, we can use the formula:
MA = output force / input force
In this case, the input force is the force applied by the construction worker without the lever, which is 27.5 N. The output force is the force applied by the lever, which is 10.0 N. Therefore, we have:
MA = 10.0 N / 27.5 N
MA ≈ 0.364
So the mechanical advantage of the lever in lifting the heavy rock is approximately 0.364. This means that the lever reduces the amount of force required to lift the rock by a factor of 0.364, but it also increases the distance over which the force must be applied.
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a 35 μf capacitor is connected to a 60-hz, 120 v supply. what is the xc of the capacitor?
The reactance of the capacitor is 452.39 Ω, which represents the opposition of the capacitor to the flow of AC current in the circuit.
In AC circuits, the impedance of a capacitor is given by its reactance, which is represented by the symbol Xc. The reactance of a capacitor is dependent on the frequency of the applied voltage and the capacitance of the capacitor.
Use formula:
Xc = [tex]1 / (2 * \pi * f * C)[/tex]
where π: mathematical constant pi, f: frequency of applied voltage, and C: capacitance of the capacitor.
In this case, the capacitance C is given as 35 μF (microfarads), and the frequency f is 60 Hz.
Put values:
Xc =[tex]1 / (2 * \pi * 60 * 35 * 10^(-6))[/tex]
Xc = 452.39 Ω (ohms)
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Energy of an object by virtue of its position is called _____________.A. Solar energyB. Mechanical energyC. Muscular energyD. Potential energy
Answer: D. Potential energy
Explanation: science
Andy has a bath and uses 1500g of water heated from 10°C to 40°C and with a specific heat capacity of 4200J/kg°C. How much energy does he use?
Andy uses 189,000 joules of energy to heat 1500g of water from 10°C to 40°C.
How to find how much energy Andy usedThe amount of energy used to heat the water can be calculated using the formula:
Q = m * c * ΔT
where:
Q = amount of energy used (in joules)
m = mass of water (in kilograms) = 1500 g / 1000 = 1.5 kg
c = specific heat capacity of water (4200 J/kg°C)
ΔT = change in temperature (in °C)
plugging in the values into the formula:
Q = 1.5 kg * 4200 J/kg°C * (40°C - 10°C)
Q = 1.5 kg * 4200 J/kg°C * 30°C
Q = 189,000 joules
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