1answer.
Ask question
Login Signup
Ask question
All categories
  • English
  • Mathematics
  • Social Studies
  • Business
  • History
  • Health
  • Geography
  • Biology
  • Physics
  • Chemistry
  • Computers and Technology
  • Arts
  • World Languages
  • Spanish
  • French
  • German
  • Advanced Placement (AP)
  • SAT
  • Medicine
  • Law
  • Engineering
Reika [66]
2 years ago
6

An object thrown vertically upward from the surface of a celestial body at a velocity of 36 ​m/s reaches a height of sequalsminu

s0.9tsquaredplus36t meters in t seconds. a. Determine the velocity v of the object after t seconds. b. When does the object reach its highest​ point? c. What is the height of the object at the highest​ point? d. When does the object strike the​ ground? e. With what velocity does the object strike the​ ground? f. On what intervals is the speed​ increasing?
Physics
1 answer:
Anarel [89]2 years ago
4 0

Answer:

v = -1.8t+36

20 seconds

360 m

40 seconds

36 m/s

The object speed will increase when it is coming down from its highest height.

Explanation:

s=-0.9t^2+36t

Differentiating with respect to time we get

\frac{ds}{dt}=-1.8t+36\\\Rightarrow v=-1.8t+36

a) Velocity of the object after t seconds is v = -1.8t+36

At the highest point v will be 0

0=-1.8t+36\\\Rightarrow t=\frac{-36}{-1.8}\\\Rightarrow t=20\ s

b) The object will reach the highest point after 20 seconds

s=-0.9t^2+36t\\\Rightarrow s=-0.9\times 20^2+36\times 20\\\Rightarrow s=360\ m

c) Highest point the object will reach is 360 m

s=-0.9t^2+36t\\\Rightarrow 360=-0.9t^2+36t\\\Rightarrow -0.9t^2+36t-360=0\\\Rightarrow -9t^2+360t-3600=0

\frac{-360\pm \sqrt{0}}{2\left(-9\right)}\\\Rightarrow t=20\ s

d) Time taken to strike the ground would be 20+20 = 40 seconds

[tex]v=u+at\\\Rightarrow v=0+0.9\times 2\times 20\\\Rightarrow v=36\ m/s

Acceleration will be taken as positive because the object is going down. Hence, the sign changes. 2 is multiplied because the expression is given in the form of s=ut+\frac{1}{2}at^2

e) The velocity with which the object strikes the ground will be 36 m/s

f) The speed will increase when the object has gone up and for 20 seconds and falls down for 20 seconds. The object speed will increase when it is coming down from its highest height.

You might be interested in
Object 1 has a mass of 99.2 kg. Object 2 has a mass of 42.3 kg. If the 2 object pust against each other, what will be the speed
Vlad1618 [11]
Djdjkesbbdjsjsjsjssjsjks
7 0
2 years ago
Can someone answer these?
scoray [572]

Nine

<em><u>Remark</u></em>

Nine is just a super problem. You understand 9 thoroughly and I guarantee a good mark. It goes to the very heart of physics and the processes it uses.

I don't know if you know about free body diagrams. If you don't, you should. Start with the up and down forces working on the chain pulling upward. Use a circle to represent the center of the action.

Draw an arrow pointing to the top of the page. Label it T for Tension. Now go to the bottom of the circle. Draw two arrows going down. One of them is the boulder. Let the mass of the boulder = M

Let the Mass of the chain = m. Don't worry about the numbers. We'll get around to them later.

So far what you have is T - Mg - mg

Tension is a force.

Mg is a weight which is also a Force.

mg is a weight which is also a Force. So far you have 3 forces. What is the net result? The two weights are accelerated upwards (otherwise the boulder would never be hauled upward. Now we have

<em><u>T - Mg - mg = (m + M)a.</u></em> This is the key equation in the entire problem. We need to use the fact about T not being more that 2.5 times it's own weight.

T ≤ 2.5 * m*g Now we put that into the main equation. We'll use the upper limit. =

2.5mg - (m+M)g = (m + M)a   Now to do just a little math. (No physics). Add (m + M)g to both sides

2.5mg = (m + M)g + (m+M)a  Use the distributive property to factor this

2.5mg = (m + M)(a + g)   Divide by m + M

2.5mg/(m + M) = a + g    We need to isolate a. Subtract g

2.5mg/(m + M) - g = a     We know the entire left side. We can put numbers in at this point. It's not very elegant, but it will work.

m = mass the chain = 575 kg

M = mass of the boulder = 750 kg

g = 9.81 m/s^2

2.5*575*9.81/(575 + 750) - g = a

10.64 - 9.81 = a

a = 0.8329 m/s^2.

Note: The units are correct and the sign on a is correct. The up forces are plus and the down accelerations are minus. Everything is looking good.

The rest of the problem just uses

d = 125 meters

a = 0.8329 m/s^2

vi = 0

t = ???

<em><u>Formula</u></em>

d = vi*t + 1/2 a t^2

125 = 1/2 * 0.8329 t^2  Multiply through by 2 and divide by 0.8329

125 *2 / 0.8329 = t^2

t^2 = 300.1

t = sqrt(300.1)

t = 17.32

Answer: C

Eight

You got this one correct, or we agree that B is the answer. I'll just so a quick solution to this question

This problem is not very well worded. The only way you can get an answer is if you know something about tennis. You have to understand that when you serve, the ball goes straight up. All the forces and velocities are vertical.

Nothing is horizontal until the racket hits the ball. The 73.14 is a horizontal velocity. The question doesn't tell you that and it should

So vi = 0

vf = 73.14

ΔV = 73.14 - 0 = 73.14 m/s

contact time = 30 milliseconds = 30/1000 seconds = 0.03 seconds

mass = W/9.81

<em><u>Formula</u></em>

F = m * ΔV / time

F = (w/9.81) * 73.14  / 0.03

F = w * 248

Answer B

Ten

Ten looks easy, because the math is grade 8 or 9 math. The physics certainly is not. Einstein based some of relativity on a thought problem like this one so the problem is not trivial.

Here's the question. What does the 60N weight represent and which way is it going? Is it going up or down? and if you can decide that, which way is the acceleration (2.45 m/s^2 going, up or down)? Finally who is feeling the 60 N and what does it represent? Now the problem (the physics problem) has presented you with trouble. It is not the math.

The weight of the fish is down.

The 2.45 m/s^2 is up

9.81 of course is down (it always is)

So in order for the elevator to accelerate upward it must be going upward with a net acceleration of 9.81 + 2.45. That's because the elevator must overcome the gravitational acceleration

m*(9.81 + 2.45)  = 60N

m*12.26 = 60N

m = 60/12.26

m = 4.894 kg

Now if the fish were on the ground being held up in the air by a proud fisherman, the fish would actually weigh

F = m*g

m = 4.894

g = 9.81

F = 4.894 * 9.81 = 48 kg

Answer C


5 0
3 years ago
Mark the correct statement: a) Charges flow through a circuit b) voltage is applied across the circuit c) voltage is the ratio o
Gennadij [26K]

Answer:

The correct option is;

d) All of the above

Explanation:

a) In an electric circuit through which electric current flows, it is due to the electric charges which can be the negatively charged electrons or the positively charged protons

b) Voltage is the potential difference that results in current flowing through the circuit, therefore, the voltage is applied across the circuit through which current flows

c) The voltage which is the electric potential difference is the change in potential energy in joules of a given system due to the movement of a test charge (in Coulombs) between points in the electric field, ΔE, divided by the value of the test charge, 'q'

V = ΔE/q

Therefore, all of the above are correct.

8 0
2 years ago
Observations must be _____. <br> subjective <br> objective <br> biased <br> deductive
Dmitrij [34]
Objective
because it means<span> based on measurement, or reasoning free of bias.</span>
6 0
3 years ago
Read 2 more answers
Of the more than 2,000 known minerals approximately 95% of them belong to what mineral group?
Temka [501]
Your answer is Silicates.
5 0
3 years ago
Other questions:
  • Sb-28 a collision could occur when the distance decreases and bearing between two vessels does what?
    12·1 answer
  • Koi is climbing through a crevice and places her feet so that her body is perpendicular as shown below she then rest in this spo
    11·1 answer
  • Beaker contain 200 mL of water what is volume of water in cm cube and m cube
    8·2 answers
  • Stars only emit light within the visible spectrum of the electromagnetic spectrum.
    14·1 answer
  • In a towns water system pressure gauges in still water at street level reads 150kpa. if a pipeline connected to the system break
    10·1 answer
  • An object initially at rest accelerates at 5 meters per second2 until it attains a speed of 30 meters per second. What distance
    14·1 answer
  • A roller coaster car with a mass of 17,690 kg is moving at a speed of 5 m/s over a hill that is 87.4 m above the
    13·1 answer
  • The volume of the vessel is reduced twice,and the number of molecules is reduced three times.How the pressure will change gas?​
    7·1 answer
  • Write the name of two substance used to laminate the core of transformer​
    12·1 answer
  • Two rubber bullets (each of the same mass) are fired at the same velocity towards two different blocks of equal mass. One block
    15·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!