Give an example of a situation in which you would describe an

Earning Goal: To be able to calculate work done by a constant force directed at different angles relative to displacement

lana [24]

Answer:

the work done by the 30N force is 4156.92 J.

For this problem, they don´t ask you to determine the work of the total force applied in the block. They only want the work done for the force of 30N, with an angle of 30º respectively of the displacement and a traveled distance of 160m. So:

W=F·s·cos(α)=30N·160m·cos(30º)=4156.92J

8 0

3 years ago

The water in a river flows uniformly at a constant speed of 2.50 m/s between parallel banks 80.0 m apart. You are to deliver a p

NISA [10]

Answer:

a) The swimmer should travel perpendicular to the bank to minimize the spent in getting to the other side.

b) 133.33 m

c) 53.13°

d) 106.67 m

Explanation:

a) The swimmer should travel perpendicular to the bank to minimize the spent in getting to the other side.

b) velocity = distance * time

Let the velocity of the swimmer be $v_{s}$ = 1.5 m/s

The separation of the two sides of the river, d = 80 m

The time taken by the swimmer to get to the other end of the river bank,

$t = \frac{d}{v_{s} }$

t = 80/1.5

t = 53.33 s

The swimmer will be carried downstream by the river through a distance, s

Let the velocity of the river be $v_{r}$ = 2.5 m/s

$S = v_{r} t$

S = 53.33 * 2.5

S = 133.33 m

c) To minimize the distance traveled by the swimmer, his resultant velocity must be perpendicular to the velocity of the swimmer relative to water

That is ,

$cos \theta = \frac{v_{s} }{v_{r} } \\cos \theta = 1.5/2.5\\cos \theta = 0.6\\\theta = cos^{-1} 0.6\\\theta = 53.13^{0}$

d) Downstream velocity of the swimmer, $v_{y} = v_{s} sin \theta\\$

$v_{y} = 1.5 sin 53.13\\v_{y} = 1.2 m/s$

The vertical displacement is given by, $y = v_{y} t$

80 = 1.2 t

t = 80/1.2

t = 66.67 s

the horizontal speed,

$v_{x} = 2.5 - 1.5cos53.13\\v_{x} = 1.6 m/s$

The downstream horizontal distance of the swimmer, $x = v_{x} t$

x = 1.6 * 66.67

x = 106.67 m

7 0

3 years ago

__________energy might also be released during a chemical reaction

pentagon [3]

Kinetic energy i think

7 0

3 years ago

What do zooplankton and krill have in common?

serious [3.7K]

<h2><em>Hello, thank you for choosing brainly today. My name is Ethan and I'll be solving your question. </em><em><u>"What do zooplankton and krill have in common?"</u></em></h2>

Krill and plankton are two groups of organisms found in the ocean. Krill are species of crustacean related to shrimp, and serve as a very important link in the food chain of the sea. Plankton consist of a larger group of organisms with much more variety, including bacteria, algae, protozoans, jellyfish and some species of cephalopods.

Propulsion

The primary factor that determines whether a species is plankton or not is propulsion. Plankton organisms lack the ability to swim against the tide, and instead float from place to place on sea currents. They may be capable of some movement, and some types of plankton can even hunt for food, but none is powerful enough to make its own headway through the ocean. Adult krill are capable of swimming against currents, but their larvae and eggs fall into the plankton category.

Variation

Krill are crustaceans of the Euphausiacea order, which consists of 86 different species. Plankton, on the other hand, can come from a wide variety of different species and orders. Plankton fall into three broad categories, depending on their primary function. Phytoplankton are plant-like organisms, capable of photosynthesis. Zooplankton are animal plankton species that get their nutrients by eating other microscopic organisms. Bacterioplankton are the smallest plankton, and often serve as food for zooplankton and other lifeforms.

Appearance

Krill species have similar characteristics and generally resemble tiny shrimp. Most species reach around 2 centimeters (0.8 inches) as adults, while the largest species can reach sizes of up to 15 centimeters (5.9 inches). Plankton, on the other hand, consists of organisms of many different shapes and sizes. The smallest categories include microscopic viruses, protozoans, small crustaceans, and other tiny organisms. At the larger end of the scale, megaplankton are any plankton over 2 centimeters (0.8 inches) in size, and include large animals, such as cephalopods and jellyfish. The largest plankton is the lion's mane jellyfish, which can reach 2.5 meters (8.2 feet) in diameter and grow tentacles more than 36.5 meters (120 feet) long.

Role

Plankton and krill serve similar, but slightly different, roles in the food chain. Phytoplankton synthesize nutrients, while bacterioplankton recycle nutrients from decomposing matter in the ocean, providing some of the fundamental sources of nutrition for all ocean creatures. Zooplankton serve to concentrate those nutrients by eating smaller plankton and serving as food for larger creatures. Krill are one step up in the food chain, eating plankton and serving as a nutrient bridge from microscopic life forms to larger fish and mammals.

6 0

3 years ago

Three observers watch a train pull away from a station toward the right of the platform. Observer A is in one of the train’s car

juin [17]

Observer A is moving inside the train

so here observer A will not be able to see the change in position of train as he is standing in the same reference frame

So here as per observer A the train will remain at rest and its not moving at all

Observer B is standing on the platform so here it is a stationary reference frame which is outside the moving body

So here observer B will see the actual motion of train which is moving in forward direction away from the platform

Observer C is inside other train which is moving in opposite direction on parallel track. So as per observer C the train is coming nearer to him at faster speed then the actual speed because they are moving in opposite direction

So the distance between them will decrease at faster rate

Now as per Newton's II law

F = ma

Now if train apply the brakes the net force on it will be opposite to its motion

So we can say

- F = ma

$a = \frac{-F}{m}$

so here acceleration negative will show that train will get slower and its distance with respect to us is now increasing with less rate

It is not affected by the gravity because the gravity will cause the weight of train and this weight is always counterbalanced by normal force on the train

So there is no effect on train motion

5 0

3 years ago