A student throws a 5.0 newton ball straight up. What is the net force on the ball at its maximum height

Using Newton's Second Law, can you explain why one of the major advancements in spaceflight was the development of strong cerami

katovenus [111]

Answer:

high density can withstand high acceleration and applied forces

Heavy metals are toxic to humans,

the clay is quite abundant and in general it is not toxic

Explanation:

The selection of materials for the construction of rockets takes into account many aspects, the technical resistance to the demands of space travel, but also the abundance of the material. Heavy metals have two very serious problems. The first one, some of them are a little scarce in nature, but the most serious problem is that almost all of them are toxic to humans, for example: lead and mercury.

On the other hand, the clay is quite abundant and in general it is not toxic to living beings.

If we use Newton's second law

F = m a

let's use the concept of density

rho = m / V

m = rho V

let's substitute

F = rho V a

From this expression we see that a material with high density can withstand high acceleration and applied forces, such as those existing in spacecraft clearance and re-entry to Earth.

Unfortunately with this law there is no criterion to select a material unless its density is high, in addition to this criterion low toxicity criteria for human beings are used,

8 0

3 years ago

A 10-kg rock falls from a height of 8-m above the ground. What is the kinetic energy of the rock just before it hits the ground?

pishuonlain [190]

Answer: 800

Explanation:

1/2 x m x v^2 = m x g x h

KE = 10 x 10 x 8

KE= 800

3 0

3 years ago

Nepal has high potential for producing hydroelectricity however it is difficult too.

Stels [109]

Answer:

I'm not a scholar of hydroelectric power in Nepal, so consider my answers carefully, below.

Explanation:

High Potential: Hydroelectric power comes from the potential energy stored in a mass that is above Earth's surface. As the word "hydro" implies, the mass in this case is water. Water from snow and glacier melt, and from normal precipitation (rain) in mountainous regions eventually cascades down the mountains in fast-flowing rivers or waterfalls. Often, there are lakes or man-made reservoirs to collect and store the water before it flows down. Mt. Everest is 8848 meters tall (about 29,000 feet). If a lake forms at just 2,000 meters, one can calculate the amount of energy in each kilogram of water stored in the lake that represents the potential energy available at that altitude. 1 kg of water at 2,000 meters has potential energy, PE, according to the equation: PE = mgh, where m is the mass in kg, g is Earth's acceleration due to gravity (9.8 m/sec^2), and h is height, in meters.

PE = mGH

PE = (1 kg)*(9.8 m/sec^2)*(2,000 meters) = 19,000 kg*m/sec^2

1 kg*m/sec^2 is the SI unit for 1 Joule, a measure of energy.

This potential energy can be converted into electrical energy by releasing the water so that it can flow down to a water-powered turbine that spins magnets and coils of wire that produce electricity. The 19,000 Joules of water potential energy can be converted to electrical power, less any inefficiency in the system, such as friction.

Nepal has the natural advantage in that it has many high mountain ranges with water flows that can be used for generating electrical power. The result is low operating costs (the fuel is the flowing water) and no greenhouse gas emissions

The difficulty in developing hydroelectric power in Nepal is due to the same factor that gives it an advantage: it is difficult constructing large hydroelectric plants in such rough terrain, and the power lines that are needed to transport the power to its destination are expensive and difficult to maintain and repair.

8 0

2 years ago

A 50 kg runner runs up a flight of stairs. The runner starts out covering 3 steps every second. At the end the runner stops. Thi

nadezda [96]

To solve the problem it is necessary to take into account the concepts of kinematic equations of motion and the work done by a body.

In the case of work, we know that it is defined by,

$W = F * d$

Where,

F= Force

d = Distance

The distance in this case is a composition between number of steps and the height. Then,

$d=h*N$ , for h as the height of each step and N number of steps.

On the other hand we have the speed changes, depending on the displacement and acceleration (omitting time)

$V_f^2-V_i^2 = 2a\Delta X$

Where,

$V_f =$ Final velocity

$V_i =$ Initial Velocity

a = Acceleration

$\Delta X =$ Displacement

PART A) For the particular case of work we know then that,

$W = F*d$

$W = m*g*(h*N)$

$W = 50*9.8*(0.3*30)$

$W = 4.41kJ$

Therefore the Work to do that activity is 4.41kJ

PART B) To find the acceleration (from which we can later find the time) we start from the previously given equation,

$V_f^2-V_i^2 = 2a\Delta X$

Here,

$V_i = \frac{0.3*3}{1} = 0.90m/s\rightarrow$ 3 steps in one second

$v_f = 0$

Replacing,

$V_f^2-V_i^2 = 2a\Delta X$

$0-0.9^2=2a(30*0.3)$

Re-arrange for a,

$a = -\frac{0.9^2}{2*30*0.3}$

$a = -45*10^{-3}m/s^2$

At this point we can calculate the time, which is,

$t = \frac{\Delta V}{a}$

$t = \frac{0-0.9}{-45*10^{-3}}$

$t = 20s$

With time and work we can finally calculate the power

P = \frac{W}{t} = \frac{4.41}{20}

P = 0.2205kW

6 0

3 years ago

. Rohit had only one light source in his room. He was told by his friend that he can make the room more lighted by using mirror.

LUCKY_DIMON [66]

Answer:

very smooth and polished glass mirror

Explanation:

The best type of mirror for this would be a very smooth and polished glass mirror. A metal mirror will also work but it would need to be extremely polished. This would allow light to efficiently be reflected across the room, thus effectively adding an "extra" light source to the room. If the mirror is not smooth then the light may become distorted and not reflect properly as it is supposed to. This may defeat the entire purpose of the mirror for this scenario.

3 0

3 years ago