<span>When a person lifts the block, the block has more potential energy. Therefore the person does positive work on the block.
work = m g h
work = (4.5 kg) (9.80 m/s^2) (1.2 m)
work = 52.92 joules
The person's work on the block is 52.92 joules
When the block is being raised, the force of gravity opposes the motion. Therefore the force of gravity does negative work on the block.
work = - (force) (h)
work = - m g h
work = -(4.5 kg) (9.80 m/s^2) (1.2 m)
work = -52.92 joules
The work done by the force of gravity on the block is -52.92 joules
Note that when the block is moved horizontally, the potential energy does not change. Therefore there is no work done on the block when it moves horizontally (we are assuming that the kinetic energy does not change).</span>
Answer:
<h2>35</h2>
Explanation:
According to snell's law which states that the ratio of the sin of incidence (i) to the angle of refraction(n) is a constant for a given pair of media.
sini/sinr = n
n is the constant = refractive index
Since the diver shines light up to the surface of a flat glass-bottomed boat, the refractive index n = nw/ng
nw is the refractive index of water and ng is that of glass
sini/sinr = nw/ng
given i = 30°, nw = 1.33, ng = 1.5, r = angle the light leave the glass
On substitution;
sin 30/sinr = 1.33/1.5
1.5sin30 = 1.33sinr
sinr = 1.5sin30/1.33
sinr = 0.75/1.33
sinr = 0.5639
r = arcsin0.5639
r ≈35°
angle the light leave the glass is 35°
An experiment that involves using a Landsat satellite is given below;
Paddy lands detection through the use of Landsat-8 satellite images and object-based classification in cape town, South Africa.
<h3>What is the experiment about?</h3>
Rice is known to be one of the most vital food staples in a lot of countries, especially South Africa . Due to the irrigated rice production that tend to differs from other kinds of agricultural fields, this study was said to have created a paddy field mapping model via the use of phenological aspects, a lot of satellite sensor data, and also the use of object-based approach.
This study uses the phonological features of rice plants and also the use of an annual data regarding surface temperature (LST) to make the paddy map.
The core remote sensing data is made up of the yearly LST that is obtained from MODIS and multi-temporal Landsat-8 satellite imagery.
Based on the study, the total accuracy and kappa coefficient for the pixel-based classification method is seen to be 92% and 0.89.
Hence, An experiment that involves using a Landsat satellite is Paddy lands detection through the use of Landsat-8 satellite images and object-based classification in cape town, South Africa.
Learn more about Landsat satellite from
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Answer:9.75 m/s
Explanation:
Given
Length of ladder 
Foot the ladder is moving away with speed of 
From diagram
------1
at 
Now differentiating equation 1 w.r.t time
negative indicates distance is decreasing with time
