Answer:
the knee extensors must exert 15.87 N
Explanation:
Given the data in the question;
mass m = 4.5 kg
radius of gyration k = 23 cm = 0.23 m
angle ∅ = 30°
∝ = 1 rad/s²
distance of 3 cm from the axis of rotation at the knee r = 3 cm = 0.03 m
using the expression;
ζ = I∝
ζ = mk²∝
we substitute
ζ = 4.5 × (0.23)² × 1
ζ = 0.23805 N-m
so
from; ζ = rFsin∅
F = ζ / rsin∅
we substitute
F = 0.23805 / (0.03 × sin( 30 ° )
F = 0.23805 / (0.03 × 0.5)
F F = 0.23805 / 0.015
F = 15.87 N
Therefore, the knee extensors must exert 15.87 N
W=f*d = 5000N * 10 stories * each 4m = 200 000 J
Answer:
Part a)


Part b)
Since on the block wedge system there is no external force in horizontal direction so the Center of mass will not move in horizontal direction but in vertical direction it will move
so displacement in Y direction is given as

Explanation:
PART A)
As we know that there is no external force on the system of two masses in horizontal direction
So here the two masses will have its momentum conserved in horizontal direction
So we have

Also we know that here no friction force on the system so total energy will always remains conserved
So we have

now we have


so we have

and another block has speed

Part b)
Since on the block wedge system there is no external force in horizontal direction so the Center of mass will not move in horizontal direction but in vertical direction it will move
so displacement in Y direction is given as

Answer:Reducing mass i.e. water
Explanation:
Frequency For given mass in glass is given by

where k =stiffness of the glass
m=mass of water in glass
from the above expression we can see that if mass is inversely Proportional to frequency
thus reducing mass we can increase frequency