You are served a hot cup of coffee and room-temperature cream at a restaurant. You want to wait a few minutes before you drink the coffee, and you want it to be as hot as possible when you drink it. Should you pour the cream in the coffee:
b) Just before you drink it
c) It doesn't matter
"Temperature difference" is the driving force for the heat transfer.
Since the coffee is initially very hot and hence it will be cool down at a very fast rate.
If we add cream immediately : The temperature will initially go down for sure but then will cool down at the slower rate as coffees mixed with cream is cooler than coffee alone and therefore heat cool down rate is less. Also, the cream will increase the mass of the content in the cup and hence larger mass will take more time to cool down.
Hence cream should be added immediately
A farmer wanted to sell watermelons in the city. To reach the city, he had to cross a river. So, he embarked on the journey while it was raining. On the way, he felt hungry and thus ate one of the watermelons. Further on a certain distance, he came across a Shark. In order to save himself, he hit the shark with the watermelon.
At this point of time, can you find out if there is any change in the water level?
When he is rowing the boat in the river, the boat is floating with watermelons in it and, therefore, all the watermelons have already displaced the water equal to their volume. Hence, there won't be any change in the water level, whether the farmer eats it or throws them away.
As shown in picture, there are four gears with the following specification
* Gear A has 60 teeth
* Gear B has 40 teeth
* Gear C has 20 teeth
* Gear D has 60 teeth
* Every minute, Gear B makes 15 complete turns.
You have a broom which you balance on your finger keeping your finger exactly on the broom's center of gravity. You mark that point with the help of a marker. Now you cut the broom from there and are left with two different pieces one of which is longer than the other. The longer piece has the handle part whereas the shorter one comprises of bristles and some party of the handle.
Now, if you weigh the two pieces, which one of them will weigh more?
The torque needed to hold up the longer piece is responsible for the fact that the shorter piece will weigh more. This is the reason why a heavier kid sits closer in on a see-saw against a lighter kid.
You are lying on a beach with a wine bottle enjoying the bright sun. After it goes empty, you friend secures the mouth of the bottle with a cork. You can see a metal ring inside the bottle that has been suspended by a string.
He asks you if you can think of any way to drop the metal ring inside the bottle without touching the bottle or the cork. Can you think of any way?
AS you can see the picture, all you have to do is analyze it and tell who all from the pictured people will die if the person at E pushes the round object to the slide on the slope. Keep in mind all the physics and the terrain while you analyze the things.
If you notice the animated gif, you know that D, C and B are going to die. D dies directly after coming in contact with the object, C dies after being thrust by the spikes of the see-saw and B dies with the blue ball.
But consider the situation that the person at E stands for Ebola. Eventually A dies as well.