Two students (X and Y) measured the diameter of a gold coin four times. The results were recorded in the table below. The actual diameter
of the coin is 28.0 mm.
a) Which student (x or Y) had measurements that are precise but not
accurate?
b) Which student (X or Y) had measurements precise and accurate?

Explanation:

To solve this problem, we need to understand the concept of precision and accuracy.

Through this understanding we apply to solve this problem.

For example; if the true value is 28.0mm and the following readings were made:

        A  =  24.0mm, 24.0mm, 24.3mm, 23.9mm  This is a precise measurement but not accurate.

      B  =  27.9mm, 28.0mm, 28.1mm:  This is an accurate measurement because it is close to the true value.

first let us lay out the formula for potential

and kinetic energy:

pe = mgh

ke = (mv^2)/2

where: m=mass, v=velocity, g=gravitational

acceleration, h=height

calculating for mass using the known values of

pe:

340j = m (9.81 m/s^2) (50ft) (1m/3.28ft)

m = 2.27 kg

the law of conservation of energy states that

energy is neither created nor destroyed. therefore, the change in kinetic

energy from 50 ft to 35 ft would be equal to the change in potential energy

from 50 ft to 35 ft. however it would be opposite in signs since one is losing

while other is gaining.

ke(35ft) – ke(50ft) = - [ pe(35ft) – pe(50ft]

ke(50ft) = 0 since the brick is initially at rest

ke(35ft) = 340j - 2.27kg (9.81 m/s^2) (35ft)

(1m/3.28 ft)

ke(35ft)

= 102.38 j