Answer:Orient your line of sight directly above the measurement markings.
Explanation: parallax error is a type of systematic error that occurs when an observer views a measurement marking at a wrong angle. This causes a noticeable disparity in results obtained. Therefore the best way to prevent this error is to view and record the data from the correct angle. This can be obtained by:
-Place the measurement device on its edge so it is level with the object being measured.
-Seek out the finest possible edge of the measurement device, or use a device with finer edges.
In conclusion, ask other observers to also take the reading and get an average of their results. It can help cancel out parallax error results.
Answer:
The spring constant = 9.25 N/m
Explanation:
The equation of an object attached to a spring that is oscillating is
T = 2π√(m/k)
Where T = period of the oscillation, m = mass of the object, k = spring constant.
Making k the subject of the equation,
k = 4π²m/T²......................... Equation 1
Note: Period(T) is the time taken to complete one oscillation
Given: T = t/10 = 9.0/10 = 0.9 s, m = 190 g = 0.19 kg.
Constant: π = 3.14
Substitute these values into equation 1.
k = 4(3.14)²(0.19)/0.9²
k = 7.4933/0.81
k = 9.25 N/m
Thus the spring constant = 9.25 N/m
Answer:
D. zero
Explanation:
For momentum of an isolated or closed system to be conserved (initial momentum must equal final momentum), the net external force acting on the system must be zero.
There is always external forces acting on a system, for this system’s momentum to remain constant, all the external forces acting on the system must cancel out, so that the net external force on the system is zero.

Therefore, the correct option is "D"
D. zero
The size of the forces between you and the planet you're on is
your weight on that planet.
Don't forget that you pull the planet with a force equal to the force
that the planet pulls on you. Your weight on Earth is the same as
the Earth's weight on you !
Optical Telescopes....................................