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gtnhenbr [62]
2 years ago
14

An athlete is working out in the weight room. He steadily holds 50 kilograms above his head for 10 seconds. Which statement is t

rue about this situation?
The athlete isn’t doing any work because he doesn’t move the weight.
The athlete isn’t doing any work because he doesn’t hold the weight long enough.
The athlete is doing work because he prevents the weight from falling downward.
The athlete is doing work because 50 kilograms is a significant load to lift.
Physics
2 answers:
Kamila [148]2 years ago
7 0

Answer: The true statement form the given statements is "the athlete is not doing any work because he does not move the weight.".

Explanation:

The formula for work done is as follows,

W = Fscos\theta

Here, F is the force, s is the displacement and theta is the angle between force and displacement.

In the given problem, an athlete holds 50 kg on his head for 10 seconds. The angle between force and displacement is 90 degree.

In this case, the work done is zero.

Therefore, the athlete is not doing any work because he does not move the weight.

Nataly_w [17]2 years ago
4 0
<span>The athlete is sweating, straining, sweating, trembling and groaning. 
But if he passed high school physics, then he may remember that
'work' in physics means (force) x (distance).  If there's no distance,
then there's no work. 

He realizes that he isn’t doing any work because he's not moving the weight.</span>
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Now suppose the initial velocity of the train is 4 m/s and the hill is 4 meters tall. If the train has a mass of 30000 kg, what
hoa [83]

Answer:

<h2>187,500N/m</h2>

Explanation:

From the question, the kinectic energy of the train will be equal to the energy stored in the spring.

Kinetic energy = 1/2 mv² and energy stored in a spring E = 1/2 ke².

Equating both we will have;

1/2 mv² = 1/2ke²

mv² = ke²

m is the mass of the train

v is the velocity of then train

k is the spring constant

e is the extension caused by the spring.

Given m = 30000kg, v = 4 m/s, e = 4 - 2.4 = 1.6m

Substituting this values into the formula will give;

30000*4² =  k*1.6²

k = \frac{30,000*16}{1.6^2}\\ \\k = \frac{480,000}{2.56}\\ \\k = 187,500Nm^{-1}

The value of the spring constant is 187,500N/m

7 0
1 year ago
. 30
schepotkina [342]

Answer:

Explanation:

Length if the bar is 1m=100cm

The tip of the bar serves as fulcrum

A force of 20N (upward) is applied at the tip of the other end. Then, the force is 100cm from the fulcrum

The crate lid is 2cm from the fulcrum, let the force (downward) acting on the crate be F.

Using moment

Sum of the moments of all forces about any point in the plane must be zero.

Let take moment about the fulcrum

100×20-F×2=0

2000-2F=0

2F=2000

Then, F=1000N

The force acting in the crate lid is 1000N

Option D is correct

7 0
1 year ago
While practicing S-turns, a consistently smaller half-circle is made on one side of the road than on the other, and this turn is
erica [24]

Answer:

The answer is "4-5-6 because the bank is growing too quickly in the beginning of its turn".

Explanation:

The S-turns is also known as the reference technique, in which the ground track of the aircraft on both sides of a defined ground-based straight-line distance represents 2 different but equivalent circles.  

Throughout the S-turns, on either side of the road, a progressively smaller half-circle is formed, and this turn does not stop until the road or reference line is crossed during the early part of the turn, the twists increase too quickly.

5 0
1 year ago
A tin can whirled on the end of a string moves in a circle because
Ilya [14]

Answer:

There is an inward force acting on the can

Explanation:

This inward force is known as Centripetal force and it is responsible for making the can whirl on the end of a string in circle and it is also directed towards the center around which the can is moving.

8 0
2 years ago
An electric clock is hanging on a wall. As you are watching the second hand rotate, the clock's battery stops functioning, and t
Setler [38]

Answer:

B. W is positive and a is negative

Explanation:

As we know that the angular speed of the second clock is in positive direction so as it comes to halt from its initial direction of motion then we have

initial angular velocity is termed as positive angular velocity

\omega = positive

now it comes to stop so angular acceleration is taken in opposite to the direction of angular speed

so we will have

\alpha = negative

so here correct answer is

B. W is positive and a is negative

8 0
1 year ago
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