Answer:
697 m
Explanation:
From the question above,
Note: Alice hears the splash of the rock in the well through the help of echo.
Applying,
v = 2x/t........................ Equation 1
Where v = speed of sound, x = depth of the well, t = time.
make x the subject of the formula in equation 1
x = vt/2................... Equation 2.
Given: v = 340 m/s, t = 4.1 s
Substitute these values into equation 2
x = 340(4.1)/2
x = 697 m.
Answer:
its two valence electrons
Explanation:
Calcium is a group 2 element with two valence electrons. Therefore, it is very reactive and gives up electrons in chemical reactions.
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Answer:
It is called force of friction
Explanation:
The force of friction is a force that acts between two objects whose surfaces are in contact with each other.
Consider the typical case of an object sliding along a certain surface. There are two types of frictions:
- Static friction: this is the force of friction that acts when the object is not in motion yet. If you push the object forward with a force F, the object will not move immediately, but it will "oppose" to this motion with a force of static friction exactly equal to the push applied:

However, this force of static friction has a maximum value, which is given by

where
is the coefficient of static friction
N is the normal reaction exerted by the surface on the object
So, when
becomes greater than
, the static friction is no longer able to balance the push applied, and the object will start sliding forward.
- Kinetic friction: this is the force of friction that acts when the object is already in motion. Its magnitude is given by

where
is the coefficient of kinetic friction, and its value is generally smaller than
. The direction of this force is also opposite to the direction of motion of the object.
1 m/s
Explanation:
To solve this question we use the following formula:
momentum = mass × velocity
momentum of the first car = 1000 kg × 2.5 m/s
momentum of the second car = 2500 kg × X m/s
To bring the cars at rest the momentum of the first car have to be equal to the momentul of the second car.
momentum of the first car = momentum of the second car
1000 kg × 25 m/s = 2500 kg × X m/s
X (velocity of the second car) = (1000 × 25) / 2500 = 1 m/s
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momentum
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