Lasers utilize concentrated light waves, focused precisely and used for certain applications. What are some common uses of laser
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The distance covered by car is equal to (assuming it is moving by uniform motion) the product between the car's speed and the time of the car ride, 4 h:
where
is the car's speed
is the duration of the car ride
Similarly, the distance covered by train is equal to the product between the train's speed and the duration of the train ride, 7 h:
The total distance covered is S=255 km, which is the sum of the distances covered by car and train:
which becomes
(1)
we also know that the train speed is 5 km/h greater than the car's speed:
(2)
If we put (2) into (1), we find
and if we solve it, we find
So, the car speed is 20 km/h and the train speed is 25 km/h.
where
Similarly, the distance covered by train is equal to the product between the train's speed and the duration of the train ride, 7 h:
The total distance covered is S=255 km, which is the sum of the distances covered by car and train:
which becomes
we also know that the train speed is 5 km/h greater than the car's speed:
If we put (2) into (1), we find
and if we solve it, we find
So, the car speed is 20 km/h and the train speed is 25 km/h.
When baking soda is mixed with lemon juice, bubbles are formed with the evolution of a gas. The gas is formed in the reaction is Carbon dioxide. is formed.
The change which happened in this reaction is a chemical change.
Since, in chemical change we can't bring a substance to it's actual form how it was in earlier.
Examples: burning of paper is chemical, since we can't get the fine paper again after it is burnt.
Thus, the above reaction is also a chemical change, since we can't get back the lemon juice how it was earlier.