Answer:
The value is 
Explanation:
From the question we are told that
The height is h = 2.0 m
The height of the window is 
The initial velocity of the rock is 
The angle at which it is thrown is 
Generally the vertical component of the velocity of the stone is mathematically represented as

=>
Generally the height of the window from the ground is mathematically represented as using kinematic equation as

=> 
Here g is negative -9.8 m/s^2 because the direction of the stone is against gravity
So

Solving this quadratic equation using quadratic formula we obtain
t = 0.770 s
Generally the velocity of the stone on the x axis is mathematically represented as

=> 
Generally the distance between the person throwing the rock and the window is mathematically represented as

=> 
=> 
Answer:
2 Hz.
Explanation:
Frequency is simply defined as the number of appearances of a periodic event occurring per time. It is usually measured in cycles/second.
Now, in this question, we are told that there are 2 cycles for each second.
Thus, we can say that the frequency is 2 cycles/1 s = 2 Hz.
The mass of water is 0.139 kg
Explanation:
The density of a substance is given by the equation

where
is the density
m is the mass of the substance
V is its volume
In this problem we have:
V = 139 mL is the volume of water
The density of water is:

Solving the equation for m, we find its mass:

And converting into kilograms,

Learn more about mass and density:
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Answer: 2 cm
Explanation:
Given , for a converging lens
Focal length : 
Height of object : 
Object distabce from lens : 
Using lens formula:
, we get
, where v = image distance from the lens.
On solving aboive equation , we get

Formula of Magnification :
, where h' is the height of image.
Put value of u, v and h in it , we get

Hence, the height of the image is 2 cm.