Answer:
The applied force is greater than the frictional force.
Explanation:
the chair moves at <u>a constant speed</u><u> </u><u>therefore</u><u>,</u><u> </u><u>the</u><u> </u><u>answer</u><u> </u><u>is</u><u> </u><u>not</u><u> </u><u>A</u><u> </u><u>or</u><u> </u><u>C</u><u>.</u>
if there is no friction then the chair <u>would accelerate and it would not be at a constant speed</u><u>.</u>
hence, the only possible answer is B.
Answer:
The object would weight 63 N on the Earth surface
Explanation:
We can use the general expression for the gravitational force between two objects to solve this problem, considering that in both cases, the mass of the Earth is the same. Notice as well that we know the gravitational force (weight) of the object at 3200 km from the Earth surface, which is (3200 + 6400 = 9600 km) from the center of the Earth:

Now, if the body is on the surface of the Earth, its weight (w) would be:

Now we can divide term by term the two equations above, to cancel out common factors and end up with a simple proportion:

Answer:
The can mass is 0,00359 kg or 3,59 g
Explanation:
1. Relevant Data:
Steel thickness= 0.13 mm or 0.013 mm
h=11 cm
d=6 cm
ρ=800 kg/m^3
2. Calculate mass from densisty equation:
, then 
We need to estimate the volume of the can to calculate the mass.
3. Estimate volume using differentials:
Cylinder volume equation is:

Considering that the can is an object with a hole inside, then we need to estimate the real volume of the sheet of steel.
Using differentials we have:

Then, we could say that 
Replacing the values of d, h and dD, we obtain:


4. Calculate the mass
Convert volume unit into 

Calculate mass



Answer:
The internal resistance of the cell is 0.051 ohm.
Explanation:
Given;
emf of the battery, E = 12 V
terminal voltage of the cell, V = 8.2 V
current in the circuit, I = 75 A
let the potential drop of the cell due to internal resistance (r) = Ir
The internal resistance of the cell is calculated from the equation below;
E = V + Ir
where;
r is the internal resistance of the cell

Therefore, the internal resistance of the cell is 0.051 ohm.