2. A book with a mass of 2 Kg is resting on a shelf 1.5 m off the floor. How much gravitational

A force F~ = Fx ˆı + Fy ˆ acts on a particle that

Hatshy [7]

Answer:

W = 46 J

Explanation:

We need to find the angle between the two vectors Force vector and displacement vector.

First we will find the angle α of the force vector

$tan\alpha =\frac{1}{8} \\\\\\alpha =7.125 deg\\$

Then we find the angle β of the displacement vector

$tan\beta=\frac{2}{6} \\\\beta = 18.43 deg\\$

With these two angles we can find the angle between the two vectors

∅ = α + β = 25.56 deg

The definition of work is given by the expression

$W=F*d*cos (theta)$

The absolute value of F will be:

$F=\sqrt{8^{2}+1^{2} } \\F= 8.06 N$

The absolute value of d will be:

$d=\sqrt{(6 )^{2}+(2)^{2} } \\d= 6.32m\\$

Now we have:

$W=8.06*6.32*cos(25.56)\\W=46 J$

4 0

3 years ago

What is the mass of a ball that has 29j of potential energy and is lifted 2.0m?

Salsk061 [2.6K]

Answer:

1.48kg

Explanation:

Here,

potential energy (P.E) = 29j

height (h) = 2m

acceleration due to gravity(g) =

$9.8m {s}^{ - 2}$

mass(m) = ?

we know,

P.E = mgh

or, 29 = m×9.8×2

or, 29/19.6 = m

or,m = 1.48kg

6 0

2 years ago

What is the arrangement of the forms of electromagnetic radiation according to their wavelengths?

Svetradugi [14.3K]

Gamma rays then x rays then UVA rays then visible light then IR then radio waves (from highest to lowest frequency).

6 0

3 years ago

A 60 kg skydiver is falling at a terminal velocity of 50 m/s.

marishachu [46]

Answer:

The gravitational force is definitely acting downwards towards the ground and this is equal to the weight of the skydiver.

the acceleration a = 7.8 m/s²

Explanation:

Given that :

the mass of the skydiver = 60 kg

Velocity = 50 m/s

Thus; gravitational force is definitely acting downwards towards the ground and this is equal to the weight of the skydiver.

Also; the air resistance is acting upward and the resultant of both forces = mass×acceleration

So;

mg-R = ma

60(9.8) - 120 = 60(a)

588 -120 = 60a

468 = 60a

a = $\frac{468}{60}$

a = 7.8 m/s²

Hence, the acceleration a = 7.8 m/s²

5 0

3 years ago

NEED HELP !!!!!

goblinko [34]

Answers with Explanations:

1. Answer: True

Explanation:

Muscle cramps happen especially during an "intense workout." The frequency of cramps is related to heat, thus it is important to stay hydrated all throughout the workout. Eating should be done at least 2 to 3 hours prior to workout because eating immediately before exercise leads to undigested food. Such kind of food causes cramps.

2. Answer: True

Explanation: Applying direct pressure immediately after the injury can help decrease bleeding. Blood loss results to blood that is collected under the skin. This turns into the color of blue or black, also known as "bruise." Decrease bleeding would then mean decrease bruising.

Applying pressure also decreases swelling because it restricts the blood flow and fluid from reaching into the injury.

3. Answer: False

Explanation: "Lordosis" refers to the body's natural lordotic curve. This is considered "normal." The excessive inward curve of the lumbar spine is called "hyperlordosis." This is commonly caused by poor posture, lack of exercise, obesity and spinal conditions.

4. Answer: False

Explanation: The mnemonic acronym "RICE" stands for Rest, Ice, Compression (not Cold) and Elevation. This term is commonly used in First Aid and was introduced by Gabe Mirkin in 1978.

5. Answer: True

Explanation: Keeping the proper posture during exercise prevents the body from encountering injuries. It also ensures that the body is executing the exercise by using the muscles properly.

6. Answer: False

Explanation: "Ice" is important in decreasing the swelling of the injury. It constricts the blood vessels which prevents the flow of blood and other fluids towards the site of injury.

7. Answer: False

Explanation: The spine is naturally straight if a person doesn't have a medical problem. However, scoliosis is a medical problem. It is a condition wherein a person's spine is curved, rather than being straight.

8. Answer: True

Explanation: When it comes to exercise, starting slow is the main key. It is followed by gradual building up. The increase will depend on the person's stamina. For example, starting with a warm-up, followed by a slow walk then pacing up to a brisk walk.

9. Answer: True

Explanation: Kyphosis is a spinal condition wherein the person's spine is excessively curved outward. This causes the upper back and the shoulders to be rounded. This condition is commonly called "hunchback."

10. Answer: True

Explanation: Proper posture entails the right amount of spinal curve. This means that the spine is in "neutral position." This means that the spine takes on the "S-shape." A little amount of curve results to a "flat back" while too much curve results to a "swayback."

11. Answer: all of the above

Explanation: Body posture and technique are important especially when it comes to exercise. Poor posture and technique lead to strain on joints, ligaments and injury especially to the muscles. This also puts the body out of alignment.

12. Answer: True

Explanation: Stretching is appropriately done at the end of a warm-up when the temperature has increased because at this time, the muscles are already flexible. It allows the muscles to be loosened and also aids in better performance during workouts or exercises.

13. Answer: False

Explanation: "Lifting" with your back only will result to muscle injury. There are several ways to do lifting such as "pull-ups" or "lat pull downs." This means that you are not lifting with your back only but using your other joints and muscles for lifting.

14. Answer: True

Explanation: "Warming-up" is an essential preparation before any workout because it prepares the body by increasing temperature and blood flow to the muscles. Without it, the muscles will become sore and the chance for injuries increases.

15. Answer: True

Explanation: "Cool down" is considered equally important as "warm-up." It lowers the body's temperature and lowers the amount of lactic acid that causes muscle cramping, soreness and stiffness.

16. Answer: True

Explanation: It is said that most people forget about warming up and cooling down before and after they work out. It is necessary to have 5 to 10 minutes of warm-up and cool down for every exercise routine.

17. Answer: False

Explanation: Knee extension is best done at 90 degrees angle as advised by most health experts. However, it depends on your capability and your exercise goals. For some people, extending beyond 90 degrees is beneficial.

18. Answer: True

Explanation: Tucking your belly button helps with your body's core exercise. If this is going to be done throughout the day, then surely it will strengthen the muscles. This can be done while a person is sitting down or walking.

4 0

3 years ago