Answer:
Explanation:
Young's modulus of elasticity Y = stress / strain
stress = force / cross sectional area
= weight of 15 kg / π r²
= 15 x 9.8 / 3.14 x ( .025 x 10⁻² )²
stress = 74.9 x 10⁷ N / m²
strain = Δ L / L , Δ L is change in length and L is original length
Putting the values
strain = .0168 / 2.7 =.006222
Young's modulus of elasticity Y = 74.9 x 10⁷ / .006222
= 120.88 x 10⁹ N / m² .
B, is older
Because if you look on the scale b is deeper
Answer:
B, to predict star count
Explanation:
the rest can be done with rulers, Einstein cans and public surveys, we can't predict how many stars there will be, but we can take pictures of them instead
The air and balloon themselves contract (shrink) because of contact with the very cold liquid N
