In which approximate direction is the warm front in the upper left of the weather map moving?

8. The legs of a young man are each 0.650 meters long. What is his maximum walking speed?

Norma-Jean [14]

Answer:

2.52 m/s

Explanation:

When the man takes a step, his foot is stationary while his body revolves around it. At the point when his body is directly above his foot, there will be no normal force at his maximum speed.

Sum of the forces in the radial direction:

∑F = ma

mg = m v² / r

g = v² / r

v = √(gr)

Given that r = 0.650 m:

v = √(9.8 m/s² × 0.650 m)

v = 2.52 m/s

8 0

3 years ago

A box is placed on a conveyor belt that moves with a constant speed of 1.05 m/s. The coefficient of kinetic friction between the

sveticcg [70]

Answer:

The box stops in 0.139 seconds, after moving 7.29cm (0.0729m) backwards relative to the belt.

Explanation:

As the box is initially at rest relative to the earth, it is moving backwards with a speed of 1.05m/s relative to the belt. Then, the frictional force acts on the box to make it stop relative to the belt. So, we first have to write the equations of motion of the box in each axis:

$x: f_k=ma\implies a=\frac{f_k}{m} \\\\y: N-mg=0\implies N=mg$

Since the frictional force $f_k$ is equal to $f_k=\mu_k N=\mu_k mg$ , then we have that the acceleration is:

$a=\frac{\mu_k mg}{m}=\mu_k g$

Now, from the definition of acceleration we get:

$a=\frac{v-v_0}{t}\implies t=\frac{v-v_0}{a}$

And, as the final velocity is zero because the box gets to a stop, we have:

$t=-\frac{v_0}{a}=-\frac{v_0}{\mu_k g}$

(Don't worry about the negative sign. It will disappear because the initial velocity is also negative, since we take the box initially moving backwards)

Then, plugging in the given values, we calculate the time:

$t=-\frac{(-1.05m/s)}{0.770(9.81m/s^{2})}=0.139s$

In words, the time the box takes to stop sliding relative to the belt is 0.139s.

The displacement of the box in this time, is given by the kinematics formula:

$v^{2}=v_0^{2}+2ax\implies x=-\frac{v_0^{2}}{2\mu_kg}$

Finally, we calculate the displacement:

$x=-\frac{(1.05m/s)^{2} }{2(0.770)(9.81m/s^2)}=-0.0729m=-7.29cm$

This means that the box moves 7.29cm backwards relative to the belt.

4 0

2 years ago

At the surface of Jupiter's moon Io, the acceleration due to gravity is 1.81 m/s2 . A watermelon has a weight of 40.0 N at the s

Mumz [18]

Answer

acceleration due to gravity on Jupiter's moon,g' = 1.81 m/s²

weight of water melon on earth, W = 40 N

acceleration due to gravity on earth, g = 9.8 m/s²

a) Mass on the earth surface

$M = \dfrac{W}{g}$

$M = \dfrac{40}{9.8}$

M = 4.08 Kg

b) Mass on the surface of Lo

Mass of an object remain same.

Hence, mass of object at the surface of Lo = 4.08 Kg.

c) Weight at the surface of Lo

W' = m g'

W' =4.08 x 1.81

W' = 7.38 N

8 0

2 years ago

According to the rayleigh criterion, what is the shortest object we could resolve at the 25.0 cm near point with light of wavele

Blizzard [7]

Answer:

$6.71 *10^{-5}$ rad

Explanation:

∅ = $\frac{1.22*wavelength}{D}$ = $\frac{1.22*550 * 10^{-9} }{25 * 10^{-2} }$

∅ = $6.71 *10^{-5}$ rad

The minimum resolvable angle = $6.71 *10^{-5}$ rad

7 0

2 years ago

One of the key disadvantages of buying fitness equipment is __________. A. privacy B. flexibility C. maintenance D. choice Pleas

Alex Ar [27]

Answer:

<h2>C. maintenance </h2>

Explanation:

I personally believe one key disadvantages is the cost of maintaining the equipment unlike the gym where you have to subscribe for the month or the year and forget about anything, owning the gym equipment comes with the extra cost and responsibilities of maintenance to the owners.

5 0

3 years ago