Answer:
Principal focus of a concave mirror. The principal focus of a concave mirror is a point on its principal axis to which all the light rays are parallel and close to the axis converge after reflection from the concave mirror.
Focal length of a concave mirror. The focal length of a concave mirror is the distance between its pole and the principal focus
The reflecting surface of a spherical mirror forms a part of a sphere. The centre of this sphere. This point is called the centre of curvature of the spherical mirror. Center of curvature can also be defined as the point in the centre of the sphere from which the mirror was sliced. It is represented by the letter C. Please note that the centre of curvature lies outside the mirror's reflecting surface. The centre of curvature of a concave mirror lies in front of it. However, it lies behind the mirror in case of a convex mirror.
If a concave mirror were thought of as being a slice of a sphere, then there would be a line passing through the center of the sphere and attaching to the mirror in the exact center of the mirror. This line is known as the principal axis.
Explanation:
0.566kg *(1mol/0.197 kg)= 2.87 mol gold
note how the units cancel out, if the units do not cancel out (kg/kg=1) then u did something wrong
Answer:
a) The perimeter of the rectangle is 29.4 centimeters.
b) The uncertainty in its perimeter is 0.8 centimeters.
Explanation:
a) From Geometry we remember that the perimeter of the rectangle (
), measured in centimeters, is represented by the following formula:
(1)
Where:
- Width, measured in centimeters.
- Length, measured in centimeters.
If we know that 
and 
, then the perimeter of the rectangle is:
The perimeter of the rectangle is 29.4 centimeters.
b) The uncertainty of the perimeter (
), measured in centimeters, is estimated by differences. That is:
(2)
Where:
- Uncertainty in width, measured in centimeters.
- Uncertainty in length, measured in centimeters.
If we know that 
and 
, then the uncertainty in perimeter is:
The uncertainty in its perimeter is 0.8 centimeters.
Answer:
The force of kinetic friction between the block and the floor is 2.4 N
Explanation:
The given parameters are;
The weight of the block = 8 Newtons
The velocity of the block = Constant velocity
Taking the kinetic friction for wood, 
= 0.3, we have;
The normal reaction of the block on horizontal ground, N = The weight of the block = 8 N
The force of kinetic friction between , 
= × N
Therefore, we have;
The force of kinetic friction between the block and the floor, = 0.3 × 8 N = 2.4 N.
If only I was smart then I could help you :/ no but like for real im madddd dumb sorry :(
