Acceleration is rate of change of ?

According to the graph, how many students received an 90 for their first semester grade?

SCORPION-xisa [38]

Answer:

B

Explanation:

B

4 0

3 years ago

A person has long hair hanging straight down from their head. A second person rubs a balloon with felt so that the balloon is ne

Vedmedyk [2.9K]

Answer:

The best explanation is that the first person is grounded to the earth, and his/her body either draws up negative charges from the earth, or tend to conducts negative charges to the earth, depending on the charge on the balloon.

Explanation:

The earth is an infinite store for charges. In the first case where the second person brings a negatively charged balloon towards the first person, the negative charges on the balloon induces the first person's body to tend to attract the negative charges on the balloon through the first person's body to the positive charges within the earth. In the second case when again a positively charged balloon is brought near the first person's hair, the positive charges on the balloon induce the first person's body into drawing up negative charges from within the earth. This charges, and their opposite induced charges, create an attractive force between the hair strands and the balloons.

4 0

3 years ago

An airplane flies at 150 km/hr. (a) The airplane is towing a banner that is b = 0.8 m tall and l = 25 m long. If the drag coef-

maw [93]

Answer:

Power requirement P for the banner is found to be 30.62 W
Power requirement P for the solid flat plate is found to be 653.225 W
Answer for part(c) is explained below in the explanation section and can be summarized as: The main difference between the drags and power requirements of the two objects of same size was due to their significantly different drag-coefficients. The Cd for banner was given, whereas the Cd for a flat plate is generally found to be around 1.28 which is the value we used in our calculations that resulted in a huge increase of power to tow the flat plate
Power requirement P for the smooth spherical balloon was found to be 40.08 W

Explanation:

First of all we will establish variables and equations known that are known to us to solve this question. Since we are given the velocity of the airplane:

v = velocity of airplane i.e. 150 km/hr. To convert it into m/s we will divide it by 3.6 which gives us 41.66 m/s
The density of air at s.t.p (standard temperature pressure) is given as d = 1.225 kg / m^3
The power can be determined this equation: P = F . v, where F represents the drag-force that we will need to determine and v represents the velocity of the airplane
The equation to determine drag-force is: $F = 1/2 * d * C_d * A$

In the drag-force equation Cd represents the co-efficient of drag and A represents the frontal area of the banner/plate/balloon (the object being towed)

Frontal area A of the banner is : 25 x 0.8 = 20 m^2

Part a) We will plug in in the values of Cd, d, A in the drag-force equation i.e. Fd = 1/2 * 0.06* 1.225 * 20 = 0.735 N. Now to find the power P we will use P = F . v i.e. 0.735 * 41.66 = 30.62 W

Part b) For this part the only thing that has fundamentally changed is the drag-coefficient Cd since it's now of a solid flat plate and not a banner. The drag-coefficient of a flat plate is approximately given as : Cd_fp = 1.28

Now we will plug-in our values into the same equations as above to determine drag-force and then power. i.e. Fd = 1/2 * 1.28 * 1.225 * 20 = 15.68 N. Using Fd to determine power, P = 15.68 * 41.66 = 653.225 W

Part c) The main reason for such a huge power difference between two objects of same size was due to their differing drag-coefficients, as drag-coefficients are generally large for objects that are not of a streamlined shape and leave a large wake (a zone of low air pressure behind them). The flat plate being solid had a large Cd where as the banner had a considerably low Cd and therefore a much lower power consumption

Part d) The power of a smooth sphere can be calculated in the same manner as the above two. We just have to look up the Cd of a smooth sphere which is found to be around 0.5 i.e. Cd_s = 0.5. Area of sphere A is given as : pi* r^2 (r = d / 2). Now using the same method as above:

Fd = 1/2 * 0.5 * 3.14 * 1.225 = 0.962 N

P = 0.962 * 41.66 = 40.08 W

4 0

3 years ago

Two particles each have the same mass but particle #1 has four times the charge of particle #2. Particle #1 is accelerated from

marin [14]

Answer:

v_2 = 2*v

Explanation:

Given:

- Mass of both charges = m

- Charge 1 = Q_1

- Speed of particle 1 = v

- Charge 2 = 4*Q_1

- Potential difference p.d = 10 V

Find:

What speed does particle #2 attain?

Solution:

- The force on a charged particle in an electric field is given by:

F = Q*V / r

Where, r is the distance from one end to another.

- The Net force acting on a charge accelerates it according to the Newton's second equation of motion:

F_net = m*a

- Equate the two expressions:

a = Q*V / m*r

- The speed of the particle in an electric field is given by third kinetic equation of motion.

v_f^2 - v_i^2 = 2*a*r

Where, v_f is the final velocity,

v_i is the initial velocity = 0

v_f^2 - 0 = 2*a*r

Substitute the expression for acceleration in equation of motion:

v_f^2 = 2*(Q*V / m*r)*r

v_f^2 = 2*Q*V / m

v_f = sqrt (2*Q*V / m)

- The velocity of first particle is v:

v = sqrt (20*Q / m)

- The velocity of second particle Q = 4Q

v_2 = sqrt (20*4*Q / m)

v_2 = 2*sqrt (20*Q / m)

v_2 = 2*v

3 0

3 years ago

Effect of Solvent:

Naddik [55]

1. H2O- The water completely dissolved the salt.

Alcohol- The alcohol dissolved the salt slightly.

Glycerin-The salt has not dissolved at all.

2. Water

3. Like dissolve like basically works on the principle of polarity. It means the substances which possess similar chemical properties may dissolve in each other. For example, ethanol can be dissolved in water because both are polar in nature whereas non-polar molecules can be dissolved in non-polar solvents only.

4. Generally, a solute dissolves faster in a warmer solvent than it does in a cooler solvent because particles have more energy of movement. For example, if you add the same amount of sugar to a cup of hot tea and a cup of iced tea, the sugar will dissolve faster in the hot tea.

Learn more about The choice of solvent here:-brainly.com/question/14918321

#SPJ9

6 0

1 year ago