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Rom4ik [11]
2 years ago
7

A runner runs 300 m at an average speed of 3.0 m/s. She then runs another 300m at an average

Physics
1 answer:
Kaylis [27]2 years ago
3 0

Answer:

B. 4 m/s

Explanation:

v=d/t

Running for 300 m at 3 m/s takes 100 seconds and running at 300 m at 6 m/s takes 50 seconds. 100 s + 50 s = 150 s (total time). Total distance is 600 m, so 600 m/ 150 s = 4 m/s.

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Little Tammy lines up to tackle Jackson to (unsuccessfully) prove the law of conservation of momentum. Tammy’s mass is 34.0 kg a
Naily [24]

Answer:

So Tammy must move with speed 4.76 m/s in opposite direction of Jackson

Explanation:

As per law of conservation of momentum we know that there is no external force on it

So here we can say that initial momentum of the system must be equal to the final momentum of the system

now we have

m_1v_1 + m_2v_2 = 0

final they both comes to rest so here we can say that final momentum must be zero

now we have

34 v + 54 (3 m/s) = 0

v = -4.76 m/s

8 0
1 year ago
Two climbers are on a mountain. Simon, of mass m, is sitting on a snow covered slope that makes an angle θ with the horizontal.
elena-14-01-66 [18.8K]

Answer:

Explanation:

It is required that the weight of Joe must prevent Simon from being pulled down . That means he is not slipping down but tends to be towed down . So in equilibrium , force of friction will act in upward direction on Simon.

Let in equilibrium , tension in rope be T

For balancing Joe

T = M g

For balancing Simon

friction + T = mgsinθ

μmgcosθ+T = mgsinθ

μmgcosθ+Mg = mgsinθ

M = (msinθ - μmcosθ)

M = m(sinθ - μcosθ)

5 0
1 year ago
The concrete post (Ec = 3.6 × 106 psi and αc = 5.5 × 10-6/°F) is reinforced with six steel bars, each of 78-in. diameter (Es = 2
masha68 [24]

Answer:

the normal stress induced by  the concrete post \sigma_c = 67.26 psi

the normal stress induced by the steel \sigma_s = - 1795.84 psi

Explanation:

Given that:

Modulus for elasticity for concrete post E_c = 3.6 *10^6 psi

Thermal coefficient for concrete post  \alpha _c = 5.5 *10^{-6}/^0F

Modulus for elasticity of steel bar E_s = 29*10^6psi

Thermal coefficient of steel bar \alpha _2 = 6.5*10^{-6}/^0F

Change in temperature ΔT = 80°F

Diameter of the steel rood = 7/8-in

Area of the steel rod A_s = 6(\frac{ \pi}{4} )(d_s)^2

= 6(\frac{ \pi}{4} )(\frac{7}{8} )^2

= 3.61 in²

Area of concrete parts A_c = (10)(10) - A_s

= (100 - 3.61) in²

= 96.39 in²

The total strain developed in the concrete post can be expressed as:

= [\frac{1}{E_cA_c}+\frac{1}{E_sA_s}]P=(\alpha_s-\alpha_c)(\delta T)

= [\frac{1}{(3.6*10^6)(96.39)}+\frac{1}{(29*10^6)(3.61)}]P=(6.5*10^{-6}-5.5*10^{-6})(80)

= [(2.88*10^{-9}) +(9.55*10^{-9}]P = 8.0*10^{-5}

= 1.234*10^{-8}P = 8.0*10^{-5}

P = \frac {8.0*10^{-5}}{1.234*10^{-8}}

P = 6482.98 lb

Since, the normal stress in concrete is induced as a result of temperature rise; we have the expression :

\sigma_c =\frac{P}{A_c}

\sigma_c = \frac{6482.98}{96.39}

\sigma_c = 67.26 psi

Thus, the normal stress induced by  the concrete post \sigma_c = 67.26 psi

Also; the normal stress in the steel bars  induced as a result of temperature rise is as follows:

\sigma_s = \frac{-P}{A_s}

\sigma_s =\frac{-6482.98}{3.61}

\sigma_s = - 1795.84 psi

Thus, the normal stress induced by the steel \sigma_s = - 1795.84 psi

6 0
2 years ago
Which of these is true of a chemical reaction? (a) energy is always transferred from reactants to products. (b) Energy is transf
lorasvet [3.4K]
The answer is B: energy is transferred, but it can go to the products or the reactants.
3 0
1 year ago
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Several years from now you have graduated with an engineering/physics degree from OSU and have been hired by a nanoengineering f
spayn [35]

Complete Question in order

See the first image attached

Answer and Explanation:

The three images attached discussed the solution to this question

second Image                                                                                      

Third Image                                                                                          

and Fourth Image

If the images are not clear enough right-click on it and open in a new tab

5 0
1 year ago
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