Answer:
5000J
Explanation:
Given in the question that
Heat added to the coffee cup is, ΔS = 20 J/K
The temperature of the coffee, T = 250 K
Now, using the formula for the entropy change
...........(1)
Where,
ΔS is the entropy change
ΔH is the enthalpy change
T is the temperature of the system
substituting the values in the equation (1)
we get
ΔH=250×20
ΔH=5000 J
Answer:
Option D
A mineral’s color reflects the wavelengths of light that are absorbed by the mineral.
Explanation:
Color is one of the physical properties of minerals. Many minerals have a wide range of colors but there are some minerals with one consistent color and such minerals are referred as monochromatic minerals for example azurite. Normally, the streak color tends to be less variable than the color of the whole mineral and impurities or minor chemical components in a mineral react and often control the display color of resultant mineral. Option D is incorrect since mineral's color don't reflect wavelengths of light absorbed by such minerals.
Answer:
stove
Explanation:
Chemical Energy is converted to Electrical Energy (stove) this is because electricity is taking process and the chemical are going together to create heat.
Answer:
Advantages
The main advantage in the use of pulleys is that the effort becomes less as compared to the normal lifting of the weights. In other words, it reduces the amount of actual force required to lift heavy objects. It also changes the direction of the force applied. These two advantages in the use pulleys make them an important tool for heavy lifting. It also provides a mechanical advantage.
The other advantage in the use of pulleys is that the distance between the operator and weight. There is a safe distance between them which avoids any disaster. Pulleys are easy to assemble and cost-effective. The combination of different directional pulleys can change the position of the load with little effort. Though there are moving parts in the pulley system they require less or no lubrication after installation.
Disadvantages
Apart from the above-said advantages while using pulley systems, there are several disadvantages in their use. The main disadvantage in the use of the pulley system is that it requires large space to install and operate. The mechanical advantage of pulleys can go to higher values but need more space to install them.
In some cases, the ropes/belts move over the wheel with no grooves, the chances of the slip of ropes/belts from the wheel are inevitable. If the system is installed to use for a long time, they require maintenance and regular check-up of ropes/cables as the friction between the wheels and cables/ropes occur causing wear and tear to them. Continuous use of the system makes the ropes weak. The rope may break while using the system causing damages to the operator, surrounding place and the load which is being lifted.
