If you find the mass of a sample to be 42.1 g and the actual mass is 42.0 g. your percent error would be what?

0.24%

Explanation:

To find the percent error, first subtract the actual value by the expected value.  You can ignore the sign of the difference.

42.0 - 42.1 = -0.1 = 0.1

Divide the difference by the expected value and multiply by 100%.

0.1/42.1 = 0.0024 × 100% = 0.24%

The percent error is 0.24%.

you need to give more information

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