Complete question is;
After doing some exercises on the floor, you are lying on your back with one leg pointing straight up. If you allow your leg to fall freely until it hits the floor, what is the tangential speed of your foot just before it lands? Assume the leg can be treated as a uniform rod x = 0.98 m long that pivots freely about the hip.
Answer:
Tangential speed of foot just before it lands is; v = 5.37m/s
Explanation:
Let U (potential energy) be zero on the ground.
So, initially, U = mgh
where, h = 0.98/2 = 0.49m (midpoint of the leg)
Now just before the leg hits the floor it would have kinetic energy as;
K = ½Iω²
where ω = v/r and I = ⅓mr²
So, K = ½(⅓mr²)(v/r)²
K = (1/6) × (mr²)/(v²/r²)
K = (1/6) × mv²
From principle of conservation of energy, we have;
Potential energy = Kinetic energy
Thus;
mgh = (1/6) × mv²
m will cancel out to give;
gh = (1/6)v²
Making v the subject, we have;
v = √6gh
v = √(6 × 9.81 × 0.49)
v = √28.8414
v = 5.37m/s
Translation of question
A ship is used to measure the depth of the sea using sound devices. A sound was fired at the bottom of the water and five seconds later there was a bounce. If the speed of sound in the water is 1500 m / s, then the depth of the water is
Answer:
3750 m
Explanation:
For sound to bounch back and be heard, this phenomenon is echo. Therefore, the distance traveled is 2d. Considering that speed is distance per unit time, expressed as s=d/t where d is distance, t is time and s is speed, in this case we say s=2d/t. Making d the subject of the formula then d=0.5st
Given 5 s as time and 1500 m/s as speed, we deduce that d=0.5*1500*5=3750 m
Answer:
Vc = 2.41 v
Explanation:
voltage (v) = 16 v
find the voltage between the ends of the copper rods .
applying the voltage divider theorem
Vc = V x ()
where
- Rc = resistance of copper = (l = length , a = area, ρ = resistivity of copper)
- Ri = resistance of iron = (l = length , a = area, ρ₀ = resistivity of copper)
Vc = V x ()
Vc = V x ()
Vc = V x ()
where
- ρ = resistivity of copper = 1.72 x 10^{-8} ohm.meter
- ρ₀ = resistivity of iron = 9.71 x 10^{-8} ohm.meter
Vc = 16 x ()
Vc = 2.41 v
The branch of science which deals with celestial objects, space, and the physical universe as a whole.
Online definition so if you’re using it for school work I recommend re-wording!