For fundamental frequency of a string to occur, the length of the string has to be half the wavelength. That is,
1/2y = L, where L = length of the string, y = wavelength.
Therefore,
y = 2L = 2*0.75 =1.5 m
Additionally,
y = v/f Where v = wave speed, and f = ferquncy
Then,
v = y*f = 1.5*220 = 330 m/s
Answer:
c)the gravitational forces of people is so small it is overshadowed by that of earth.
Explanation:
The gravitational force between two objects is given by:
where
G is the gravitational constant
m1 and m2 are the masses of the two objects
r is the distance between the two objects
From the formula, we see that the gravitational force depends on the masses of the objects: since the mass of the Earth (
is much much larger than the average mass of one person (80-100 kg), then the gravitational force exerted by the Earth on a person is also much much larger than the gravitational force between two people.
A single fixed pulley can be used to raise or lower lightweight objects.
Option b
<u>Explanation:</u>
A pulley is a simple machine tool which is used to make lifting or lowering tasks easy. A single fixed pulley is a system involving only one pulley fixed on a constant rigid support with a rope wrapped around the wheel. Such a system can be used only to change the direction of applied force in raising or lowering small, lightweight objects which need minimal work force.
A single fixed pulley system helps only in redirecting the applied force direction by using a rope and wheel assembly. The work done in such a case remains the same and hence it is not preferred to use it in lifting heavy objects. Neither is the required force reduced in case of a single fixed pulley system. A movable pulley helps in achieving (A) and (C).
Answer:
Explanation:
Given
mass of book(m)=2.1 kg
height up to which book is lifted is (h)2.2 m
height of person 
Potential energy of book relative to ground=mgh
(b)PE w.r.t to person head =mg(h-h0)
work done by person in lifting box 2.2 m w.r.t floor
Word done =Potential Energy of box relative to floor=45.2 J
