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Anit [1.1K]
3 years ago
10

How many foot-pounds of work does it take to throw a baseball 90 mph? a baseball weighs 5 oz, or 0.3125 lb?

Physics
1 answer:
NARA [144]3 years ago
5 0

Kinetic energy of the ball is (mv²) / 2, where m is the mass and v is the velocity

So plugging in the mass and the velocity into the kinetic energy expression, you get:

Kinetic energy of the ball = (mv²) / 2

(0.3125/32) times (132)² divided by 2 = 85 ft-lbs


Kinetic energy of the ball = 85 ft-lbs


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An object in circular motion has velocity that is constantly changing. The direction of the acceleration is
Keith_Richards [23]
<h2>Answer: Toward the center of the circle.</h2>

This situation is characteristic of the uniform circular motion , in which the movement of a body describes a circumference of a given radius with constant speed.  

However, in this movement the velocity has a constant magnitude, but its direction varies continuously.

Let's say \vec{V} is the velocity vector, whose direction is perpendicular to the radius r of the trajectory, therefore   the acceleration \vec{a} is directed toward the center of the circumference.

 

7 0
3 years ago
The dial of a scale looks like this: 00.0kg. A physicist placed a spring on it. The dial read 00.6kg. He then placed a metal cha
saveliy_v [14]

Answer:

d. The scale's resolution is too low to read the change in mass

Explanation:

If we want to find the change in energy of the spring, we will have to use the Hooke's Law. Hooke's Law states that:

F = kx

since,

w = Fd

dw = Fdx

integrating and using value of F, we get:

ΔE = (0.5)kx²

where,

ΔE = Energy added to spring

k = spring constant

x = displacement

The spring constant is typically in range of 4900 to 29400 N/m.

So if we take the extreme case of 29400 N/m and lets say we assume an unusually, extreme case of 1 m compression, we get the value of energy added to be:

ΔE = (0.5)(29400 N/m)(1 m)²

ΔE = 1.47 x 10⁴ J

Now, if we convert this energy to mass from Einstein's equation, we get:

ΔE = Δmc²

Δm = ΔE/c²

Δm = (1.47 x 10⁴ J)/(3 x 10⁸ m/s)²

<u>Δm =  4.9 x 10⁻¹³ kg</u>

As, you can see from the answer that even for the most extreme cases the value of mass associated with the additional energy is of very low magnitude.

Since, the scale only gives the mass value upto 1 decimal place.

Thus, it can not determine such a small change. So, the correct option is:

<u>d. The scale's resolution is too low to read the change in mass</u>

8 0
3 years ago
An airplane accelerates from a velocity of 22 m/s to 40 m/s with an acceleration of 2 m/s2. How long does it
andrey2020 [161]

The time it takes the plane to change its velocity is 9s.

<h3>What is time?</h3>

Time can be defined the measured or measurable period during which an action, process, or condition exists or continues.

To calculate the time it takes the airplane to change its velocity, we use the formula below.

Formula:

  • t = (v-u)/a.......... Equation 1

Where:

  • a = Acceleration
  • v = Final velocity
  • u = Initial velocity
  • t = time

From the question,

  • v = 40 m/s
  • u = 22 m/s
  • a = 2 m/s²

Substitute these values into equation  1

  • t = (40-22)/2
  • t = 18/2
  • t = 9s

Hence, the time it takes the plane to change its velocity is 9s.

Learn more about time here: brainly.com/question/2854969

4 0
1 year ago
A substance made of two or more elements is called a what
SSSSS [86.1K]
I think it’s a compound.
8 0
3 years ago
1. What is the potential energy of a 4-kilogram potted plant that is on a 1 meter-high plant
Yuri [45]

39.2 J

Explanation:

Step 1:

To find the potential energy the following formula is used.

Potential Energy = m × g × h

Where,

m = Mass

g = Acceleration due to gravity

h =  Height

Step 2:

Here m = 4 kg, g = 9.8 m/s², h = 1 m

Potential Energy = ( 4 × 9.8 × 1)

                             = 39.2 J

4 0
3 years ago
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