Is heat from the sun hitting a solar panel convection conduction or radiation
2 answers:
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Here when an object is placed on the level floor then in that case there are two forces on the object
1). Weight of object downwards (mg)
2). Normal force due to floor which will counterbalance the weight (N)
so when no force is applied on the box at that time normal force is counter balanced by weight.
Now here it is given that A person tried to lift the box upwards
So now there are two forces on the box
1). Applied force of person
2). Normal force due to ground
So now these two forces will counter balance the weight of the crate
So we can write an equation for force balance like
given that
here
m = 30 kg and
g = acceleration due to gravity = 10 m/s^2
now from above equation
So force applied by the person must be 150 N
Since the diameter of helium atom is approximately , therefore the diameter of helium atom in nano meter,
6) b) 2.7 m/s
7) b) DCA
8) b) B
Explanation:
6)
In a displacement-time plot, the slope of the line is given by
where
is the change in the y-variable, so it is the displacement
is the change in the x-variable, so it is the time elapsed
So, the slope of the line in a displacement-time plot corresponds to the velocity:
Therefore, to find the velocity of the object, we have to estimate the slope of its curve.
To estimate the velocity of object B, we have to estimate the slope of the line tangent to curve B at 10 seconds.
By doing an estimate by eye, we see that the displacement of object B changes from -10 m to 0 m when time increases from about 8 s to 12 s, so the velocity is about:
So the closest option is b) 2.7 m/s.
7)
As we said in part A, the velocity of each object is given by the slope of each curve.
Therefore:
- The steeper the curve, the higher the velocity
- The less steep the curve, the lower the velocity
From the graph, we observe that, among A, C and D:
- Curve D has the largest slope (in absolute value), so object D has the largest magnitude of the velocity
- Curve C is less steep than curve C, so object C has the second largest magnitude of velocity
- Curve A is flat, so the slope is zero, so its velocity is zero
So, from greatest magnitude to lowest magnitude of velocity, we have:
b) DCA
8)
In the graph, the overall displacement of each object is given by the change in the y-variable, .
This means that the object with largest displacement is the object whose curve has the largest variation in y.
From the graph, we see that:
- Object b has the largest variation in y, from -15 m to 30 m, so
- Then, object D has the second largest displacement (in magnitude), from -15 m to 25 m,
Finally, object C has displacement
While object A has displacement zero. Therefore, the correct option is
b) B