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Reil [10]
3 years ago
15

To develop muscle tone, a woman lifts a 2.4 kg weight held in her hand. She uses her biceps muscle to flex the lower arm through

an angle of 21°. What is the instantaneous angular acceleration if she starts her workout with her arm vertical in the downwards direction? Assume the weight is 29 cm from the elbow joint, her forearm has a moment of inertia of 0.245 kg⋅m2, and the muscle force is 850 N at an effective perpendicular lever arm of 1.7 cm in rad/s2.
Physics
1 answer:
andrey2020 [161]3 years ago
6 0

Answer:

(a) a=41.1 rad/s^2

(b) W=15.7 J

Explanation:

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LAB 11: MASSES AND SPRINGS Part A Theory Please study spring force and oscillation concepts to answer the following questions. 1
Marat540 [252]

Simple harmonic motion is defined as a periodic motion of a point along a straight line, such that its acceleration is always towards a fixed point in that line and is proportional to its distance from that point.

Why is it called simple harmonic motion?

The motion of a particle moving along a straight line with an acceleration whose direction is always towards a fixed point on the line and whose magnitude is proportional to the distance from the fixed point is called simple harmonic motion.

Why is SHM important?

Whilst simple harmonic motion is a simplification, it is still a very good approximation. Simple harmonic motion is important in research to model oscillations for example in wind turbines and vibrations in car suspensions.

What are two basic characteristics of SHM?

Solution : The two basic characteristics of a simple harmonic motion :  (i) Acceleration is directly proportional to displacement.

(ii) The direction of acceleration is always towards the mean position, that is opposite to displacement.

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7 0
1 year ago
A tennis ball rolls off the edge of a table. the table is 0.55m tall and the tennis ball lands 0.12m away from the table.
k0ka [10]

Answer:

v = 0.363 m/s

Explanation:

Given that,

The table is 0.55m tall and the tennis ball lands 0.12m away from the table.

Here, u = 0 (at rest) for initial vertical velocity as it rolls off the edge of a table.

Let t is the time to fall from the vertical height. So,

h=ut+\dfrac{1}{2}at^2\\\\t=\sqrt{\dfrac{2h}{g}} \\\\t=\sqrt{\dfrac{2\times 0.55}{9.8}} \\\\t=0.33\ s

It can be assumed to find the initial horizontal velocity of the tennis ball. It can be given by :

v_x=\dfrac{x}{t}\\\\v_x=\dfrac{0.12}{0.33}\\\\v_x=0.363\ m/s

Hence, the initial horizontal velocity is 0.363 m/s.

3 0
3 years ago
A scooter has wheels with a diameter of 120 mm. What is the angular speed of the wheels when the scooter is moving forward at 6.
nirvana33 [79]

To develop this problem we will apply the concepts related to angular kinematic movement, related to linear kinematic movement. Linear velocity can be described in terms of angular velocity as shown below,

v = r\omega \rightarrow \omega = \frac{v}{r}

Here,

v = Lineal velocity

\omega= Angular velocity

r = Radius

Our values are

v = 6/ms

r = \frac{d}{2} = \frac{120*10^{-3}}{2} = 0.06m

Replacing to find the angular velocity we have,

\omega = \frac{6m/s}{0.06m}

\omega = 100rad/s

Convert the units to RPM we have that

\omega = 100rad/s (\frac{1rev}{2\pi rad})(\frac{60s}{1m})

\omega = 955.41rpm

Therefore the angular speed of the wheels when the scooter is moving forward at 6.00 m/s is 955.41rpm

4 0
3 years ago
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77julia77 [94]

Answer: Your answer is<u> 1.36.</u>

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5 0
2 years ago
Marc and Linh stretch out a long spring on the classroom floor. Marc holds one end of the spring still. Linh creates waves in th
Soloha48 [4]

The speed of the wave created by Linh in the spring by moving the other end right and left with a frequency of 2 Hz is 1m/s.

<h3>How to calculate speed of a wave?</h3>

The speed of a wave can be calculated by using the following formula:

Speed = Wavelength x Frequency

According to this question, Linh creates waves in the spring by moving the other end right and left with a frequency of 2 Hz. If wave crests are 0.5 m apart, the speed can be calculated as follows:

speed = 2Hz × 0.5m

speed = 1m/s

Therefore, the speed of the wave created by Linh in the spring by moving the other end right and left with a frequency of 2 Hz is 1m/s.

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7 0
2 years ago
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