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Flura [38]
3 years ago
10

Help pls pls i give reward

Physics
2 answers:
ohaa [14]3 years ago
3 0

Answer:

B

Explanation:

There is no new substances formed in choice B

xz_007 [3.2K]3 years ago
3 0

Answer:

the answer is B. boiling of water, bursting of a balloon, crumpling a piece of paper.

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An athlete at the gym holds a 3.0 kg steel ball in his hand. His arm is 60 cm long and has a mass of 3.8 kg, with the center of
Serggg [28]

Answer:

(a) τ = 26.58 Nm

(b) τ = 18.79 Nm

Explanation:

(a)

First we find the torque due to the ball in hand:

τ₁ = F₁d₁

where,

τ₁ = Torque due to ball in hand = ?

F₁ = Force due to ball in hand = m₁g = (3 kg)(9.8 m/s²) = 29.4 N

d₁ = perpendicular distance between ball and shoulder = 60 cm = 0.6 m

τ₁ = (29.4 N)(0.6 m)

τ₁ = 17.64 Nm

Now, we calculate the torque due to the his arm:

τ₁ = F₁d₁

where,

τ₂ = Torque due to arm = ?

F₂ = Force due to arm = m₂g = (3.8 kg)(9.8 m/s²) = 37.24 N

d₂ = perpendicular distance between center of mass and shoulder = 40% of 60 cm = (0.4)(60 cm) = 24 cm = 0.24 m

τ₂ = (37.24 N)(0.24 m)

τ₂ = 8.94 Nm

Since, both torques have same direction. Therefore, total torque will be:

τ = τ₁ + τ₂

τ = 17.64 Nm + 8.94 Nm

<u>τ = 26.58 Nm</u>

<u></u>

(b)

Now, the arm is at 45° below horizontal line.

First we find the torque due to the ball in hand:

τ₁ = F₁d₁

where,

τ₁ = Torque due to ball in hand = ?

F₁ = Force due to ball in hand = m₁g = (3 kg)(9.8 m/s²) = 29.4 N

42.42 cm = 0.4242 m

τ₁ = (29.4 N)(0.4242 m)

τ₁ = 12.47 Nm

Now, we calculate the torque due to the his arm:

τ₁ = F₁d₁

where,

τ₂ = Torque due to arm = ?

F₂ = Force due to arm = m₂g = (3.8 kg)(9.8 m/s²) = 37.24 N

d₂ = perpendicular distance between center of mass and shoulder = 40% of (60 cm)(Cos 45°) = (0.4)(42.42 cm) = 16.96 cm = 0.1696 m

τ₂ = (37.24 N)(0.1696 m)

τ₂ = 6.32 Nm

Since, both torques have same direction. Therefore, total torque will be:

τ = τ₁ + τ₂

τ = 12.47 Nm + 6.32 Nm

<u>τ = 18.79 Nm</u>

3 0
3 years ago
Suppose you are standing on the edge of a dock and jump straight down. If you land on sand your stopping time is much shorter th
denis-greek [22]

Answer:

In bringing you to a halt, the sand and the water exert the same impulse on you, but the sand exerts a greater average force

Explanation:

7 0
3 years ago
Magnesium is a shiny, flexible metal that can be burned in the presence of air.
alukav5142 [94]

Answer:

A new substance was formed

Explanation:

According to this question, a shiny and flexible metal called Magnesium (Mg) is burnt in air to produce a white powder that has no shiny or flexible properties, however, has more weight than the magnesium metal itself.

This is possible because a CHEMICAL CHANGE has occured, hence, a new substance has been formed. The formation of a new substance during the burning process (chemical reaction), induced the increase in mass.

8 0
3 years ago
What are three ways the electricity we use can be generated
Rufina [12.5K]
There are 3 different types of energy. These 3 are fossil fuel, nuclear energy, and renewable energy. Most electricity is generated by ether wind, solar, or thermoelectric. Thermoelectric produces energy by burning coal,natural gas, and oil in a boiler.
3 0
2 years ago
A small rocket with mass 20.0 kg is moving in free fall toward the earth. Air resistance can be neglected. When the rocket is 80
Mekhanik [1.2K]

Answer:

= 308.5 N

Explanation:

acceleration  of rocket for safe landing

v_{y} ^{2} = v_{0} ^{2} +2ay

a = \frac{v_{y}^{2} - v_{0}^{2}  }{2y}

v_{0} = initial velocity

v_{y} =final Velocity

m = mass of rocket

\frac{0^{2} - 30^{2}  }{2\times80}

-5.625 m/s^{2}

Upward force

F - mg = ma

F = ma+ mg

F = m(a+g)

m= mass

a = 5.625 m/s^{2}

g = 9.8m/s^{2}

= 20(5.625 m/s^{2}+ 9.8m/s^{2})

= 308.5 N

7 0
3 years ago
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