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
tekilochka [14]
3 years ago
14

For each of the motions described below, determine the algebraic sign (+, -, or 0) of the velocity and acceleration of the objec

t at the time specified. For all of the motions, the positive y axis is upward.
Part A
An elevator is moving downward when someone presses the emergency stop button. The elevator comes to rest a short time later. Give the signs for the velocity and the acceleration of the elevator after the button has been pressed but before the elevator has stopped.
Enter the correct sign for the elevator's velocity and the correct sign for the elevator's acceleration, separated by a comma. For example, if you think that the velocity is positive and the acceleration is negative, then you would enter +,- . If you think that both are zero, then you would enter 0,0 .


Part B
A child throws a baseball directly upward. What are the signs of the velocity and acceleration of the ball immediately after the ball leaves the child's hand?
Enter the correct sign for the baseball's velocity and the correct sign for the baseball's acceleration, separated by a comma. For example, if you think that the velocity is positive and the acceleration is negative, then you would enter +,- . If you think that both are zero, then you would enter 0,0 .


Part C
A child throws a baseball directly upward. What are the signs of the velocity and acceleration of the ball at the very top of the ball's motion (i.e., the point of maximum height)?
Enter the correct sign for the baseball's velocity and the correct sign for the baseball's acceleration, separated by a comma. For example, if you think that the velocity is positive and the acceleration is negative, then you would enter +,- . If you think that both are zero, then you would enter 0,0 .
Physics
1 answer:
evablogger [386]3 years ago
7 0

Part A: -,+

The elevator is moving downward, this is what determines the direction of the velocity, as it will follow the direction of the movement. As we are told that the positive direction is upward, then the velocity has negative direction. Also, after the button is pressed, the elevator starts to stop, in other words, its velocity starts to decreased. This means that the acceleration has an opposite direction to the velocity, therefore, its sign is +.

Part B: +, -

The ball is moving upward, and as said before, this is what determines the direction of the velocity, as it will follow the direction of the movement. Then, velocity has a + sign.

Also, after the ball is thrown, there is no other force other than gravity, which will oppose to the movement of the ball, trying to make it come back to the ground. This means that the acceleration has an opposite direction to the velocity, in other words, it's directed downward, therefore, its sign is -.

Part C: 0, -

The acceleration of the ball since it was thrown until it fell to the ground will always be the gravity, which will always go downward (-).

After being thrown, the ball's velocity will start to decrease because of gravity. When its velocity has turned to 0, the ball will have reached maximum height . At this point it will start to fall again, accelerated by gravity. But at the very top, the velocity of the ball is 0.

You might be interested in
A 2.50-m segment of wire carries 1000 A current and feels a 4.00-N repulsive force from a parallel wire 5.00 cm away. What is th
Stolb23 [73]

Answer:

The current is  I_b  =  400 \ A

Explanation:

From the question we are told that

    The  length of the segment is  l  =  2.50  \  m

     The current is  I_a  =  1000 \ A

     The force felt is  F  =  4.0 \  N

        The distance of the second wire is  d =  5.0 \ cm  = 0.05 \  m

Generally the current on the second wire is mathematically represented as

        I_b  =  \frac{2 \pi * r * F }{ l *  \mu_o  *  I_a }

Here  \mu_o is the permeability of free space with value  \mu_o =  4 \pi * 10^{-7} \ N/A^2

=>      I_b  =  \frac{2 * 3.142  *  0.05 *  4 }{ 2.50  *  4\pi *10^{-7}  * 1000 }

=>      I_b  =  400 \ A

4 0
2 years ago
The movement of protons through atp synthase occurs from the
Lera25 [3.4K]

Answer:

cytoplasm and channel gates

Explanation:

The movement originates from the cytoplasm. This is the fluid medium through which ions are shuttle from one place to another. However, though simple as it might appear to be, the movement requires carrier proteins. The are proteins that facilitate in the movement of the ions. These proteins have specially controlled gates called channel proteins. These are regulated proteins that open and close based on hydrogen ion concentration. These proteins are able to facilitate the movement of ATP molecules.

5 0
3 years ago
Write a sentence to describe how an image is formed on retina<br>when looking at distant objects.​
beks73 [17]

Answer:

An image is formed on the retina with light rays converging most at the cornea and upon entering and exiting the lens. Rays from the top and bottom of the object are traced and produce an inverted real image on the retina. The distance to the object is drawn smaller than scale

7 0
3 years ago
what is the magnitude of the electric force between charges of 0.25 C and 0.11 C at a separation of 0.88 m? if the separation be
leonid [27]
F = k \cdot \frac{q_1 q_2}{d} = 9 \cdot 10^{9} \cdot \frac{0.25 \cdot 0.11}{0.88} =  144 \cdot 5^{9} \ N.

If the separation between the charges is increased then the magnitude of the force will increase in fact how the distance is being used in that formula.
6 0
2 years ago
What is a normal force?
Flauer [41]
Is the component perpendicular to the surface on contact  of the  contact force  <span />
3 0
3 years ago
Other questions:
  • Does displacement = Δx?
    13·2 answers
  • Four compasses are placed around a wire, as shown. What is the best conclusion that can be drawn?
    10·2 answers
  • In the water cycle, which state of matter has the particles closest together?
    9·2 answers
  • An inquisitive physics student and mountain climber climbs a 48.0-m-high cliff that overhangs a calm pool of water. He throws tw
    9·1 answer
  • Spinning situations???
    13·2 answers
  • You're driving your pickup truck around a curve that has a radius of 17 m.
    9·1 answer
  • What is the phase of the Moon if it . . .
    10·1 answer
  • The cheetah can run a distance of 275 m for 9 seconds. Calculate its speed.
    14·1 answer
  • If the ball has a positive electric charge, what should the charge of the coilgun be to push the ball away?
    12·1 answer
  • Circle the letter that corresponds to the best answer.
    6·1 answer
Add answer
Login
Not registered? Fast signup
Signup
Login Signup
Ask question!