TV broadcast antennas are the tallest artificial structures on Earth. In 1987, a 72.0 kg physicist placed himself and 400 kg of equipment at the top of one 610 m high antenna to perform gravity experiments. By how much was the antenna compressed, if we consider it to be equivalent to a steel cylinder 0.150 m in radius. a)190 km b)190 cm

c)190 mm

d)190 μm

190μm

Explanation:

Given the following :

Mass of physicist (m1)= 72kg

Mass of equipment(m2) = 400kg

Height of antenna (L) = 610m

Radius(r) = 0.150

Youngs modulus of steel = 2 × 10^11 Nm^-2

Recall the young's modulus(y) formula :

Y = stress / strain

Stress = force (F) / area(A)

Strain = extension(E) / length (L)

Y = (F/A) ÷ (E/L)

Y = F/A × L/E

Y = FL /AE

Y × AE = FL

E = FL / YA

Area(A) = πr^2

A = π × 0.150^2 = 0.070695m^2

Force (F) = mg

(400 + 72) × 9.8m/s^2 = 4625.6N

THEREFORE :

E = (4625.6 × 610) / (2 × 10^11 × 0.070695)

E = 2821616 / 0.14139 × 10^11

E = 2821616 / 14139000000

E = 0.00019956262819152

E = 0.0001995

E = 1.995 × 10^-4m = 199.5 × 10^-6

Approx E = 190μm

i think it’s a. this is because if they measured the mass of something with a mass of 150g, then their final answer would have to be approximately 150g. though all of their answers are almost 150, rosa and tran have the closest answers (or the exact answer) to the accurate one.

i think the answer is a and b

i wish you luck