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3 years ago

Which of the following is a benefit of physical activity?

Physics

2 answers:

IgorC [24]3 years ago

8 0

The answer should be : b

zaharov [31]3 years ago

5 0

Answer:

Explanation:

better concentration

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A 6.60-kg block slides with an initial speed of 1.56 m/s up a ramp inclined at an angle of 28.4° with the horizontal. The coeffi

Vlad [161]

Answer:

The distance travel by block before coming to rest is 0.122 m

Explanation:

Given:

Mass of block $m = 6.60$ kg

Initial speed of block $v _{i} = 1.56$ $\frac{m}{s}$

Final speed of block $v_{f} = 0$ $\frac{m}{s}$

Coefficient of kinetic friction $\mu _{k} = 0.62$

Ramp inclined at angle $\theta =$ 28.4°

Using conservation of energy,

Work done by frictional force is equal to change in energy,

$\mu _{k} mgd \cos 28.4 = \Delta K - \Delta U$

Where $\Delta U = mg d\sin 28.4$

$\mu _{k} mgd \cos 28.4 = \frac{1}{2}mv_{i} ^{2} - mgd\sin 28.4$

$\mu _{k} mgd \cos 28.4 +mgd\sin 28.4 = \frac{1}{2}mv_{i} ^{2}$

$d(6.60 \times 9.8 \times 0.62 \times 0.879 + 6.60 \times 9.8 \times 0.475) = \frac{1}{2} \times 6.60 \times (1.56)^{2}$

$d = 0.122$ m

Therefore, the distance travel by block before coming to rest is 0.122 m

7 0

3 years ago

A woman stands on a bathroom scale in a motionless elevator. When the elevator begins to move, the scale briefly reads only 0.64

Galina-37 [17]

Answer:

The downwards acceleration is 3.53 m/s2.

Explanation:

Let the true weight is m g.

The reading of the balance, R = 0.64 mg

Let the acceleration is a.

As the apparent weight is less than the true weight so the elevator goes down wards with some acceleration.

Use Newton's second law

m g - R = m a

m g - 0.64 m g = m a

0.36 g = a

a = 3.53 m/s2

6 0

3 years ago

What is system thinking ?

Greeley [361]

Answer: Systems thinking is a holistic approach to analysis that focuses on the way that a system's constituent parts interrelate and how systems work over time and within the context of larger systems.

7 0

3 years ago

Consider two less-than-desirable options. In the first you are driving 30 mph and crash head-on into an identical car also going

Nutka1998 [239]

The greater force is hitting the other car, since the force of the head on collision is added to your forward force.

6 0

3 years ago

Suppose you are helping Galileo measure the acceleration due to gravity by dropping a canon ball from the tower of Pisa, You mea

Anni [7]

It is given that the height of the tower is

$h=183 ft.$

The uncertainty the measurement of this height is

$\Delta h=0.2 ft$

Drop time is measured as:

$t=3.5s$

The uncertainty in measurement of time is:

$\Delta t=0.5 s$

Using the equation of motion: $h=ut+\frac{1}{2} at^2$ where, $h$ is the distance covered, $u$ is the initial velocity, $a$ is the acceleration and $t$ is the time.

$u=0$ (because canon ball is in free fall). we need to calculate the value of a=g.

$\Rightarrow h=\frac{1}{2}gt^2$

$\Rightarrow g=\frac{2h}{t^2}\\ \Rightarrow g=\frac{2\times 183ft}{(3.5s)^2}=29.87 ft/s^2$

The uncertainty in this value is given by:

$\Delta g=g\sqrt{(\frac{\Delta h}{h})^2+(\frac{2\Delta t}{t})^2}$

Substitute the values:

$\Delta g=29.87\sqrt{(\frac{0.2 }{183})^2+(\frac{2\times 0.5}{3.5})^2}=29.87\sqrt{1.19\times 10^{-6}+0.08}=29.87\times \sqrt{0.08}=29.87\times 0.28=8.44 ft/s^2$

5 0

3 years ago