10/9
Explanation:
option 2 is the correct answer
Answer:
Friction between the box and the floor is 25N to the left
Explanation:
There are two forces acting on the box along the horizontal direction:
- The force of push applied by the worker, in the forward direction, F
- The force of friction, , acting in the opposite direction (backward)
So the net force acting on the box is
According to Newton's second law of motion, the net force on an object is equal to the product between its mass (m) and its acceleration (a), so we can write:
And so
However, in this case the box is moving at constant speed; this means that its acceleration is zero:
Therefore we have:
Which means
And since we are told that
This means that the force of friction is also 25 N:
As the bright sun shines upon the water, the water slowly dissapears. This is an example of physical change because here the water is just transformed into water vapour. So only the state and the shape of the substance has changed. Its originality remains absolutely intact. In the second case where the same sunlight gives energy to the surrounding plants to convert water and carbon dioxide into sugar and oxygen gas, it is a chemical change. here new substances are formed and the identity of the original substances are lost.In chemical reactions, the mass of the product will always be the same as the mass of the reactants.
Answer:
1.25 focal lengths
Explanation:
The lens equation states that:
where
f is the focal length
p is the object distance
q is the image distance
In this problem, the image is 4 times as far from the lens as is the object: this means that
If we substitute this into the lens equation and we rearrange it, we get
so, the object distance measured in focal lengths is
1.25 focal lenghts
Answer:
Explanation:
<u>Displacement Vector</u>
The displacement, as every vector, has a magnitude r and a direction angle θ measured from the positive x-axis.
If we know the x-y components of the displacement, the magnitude and angle can be calculated by the equations:
The coordinates of the given vector are x=-12 m, y=21 m, thus:
Since the vector lies in the second quadrant, we add 180° to find the correct direction: