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3 years ago

7

A running is training to compete in a marathon. During his training session he runs at anaverage speed of 4.5 m/s. If his traini

ng session lasted for 130 minutes, how long did he run?

1 answer:

Radda [10]3 years ago

8 0

Answer:

It would be 565m/s.

Explanation:

130 × 4.5=565

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A squirrel pulls a 8.7 kg bag of acorns along the ground with a constant force of 80 N. If the force of friction opposing this s

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Answer:

$a=5.51\ m/s^2$

Explanation:

Given that,

The mass of a bag of acorns, m = 8.5 kg

The force acting on the bag = 80 N

The force of friction = 32 N

We need to find the acceleration of the bag of acorns.

Net force acting on it is = 80 N - 32 N

= 48 N

Let a be the acceleration of the bag of acorns. So,

F = ma

$a=\dfrac{F}{m}\\\\a=\dfrac{48}{8.7}\\\\a=5.51\ m/s^2$

So, the acceleration of the bag of acorns is $5.51\ m/s^2$ .

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3 years ago

A 33.0 g iron rod, initially at 22.7 ∘c, is submerged into an unknown mass of water at 63.3 ∘c, in an insulated container. the f

professor190 [17]

When the iron and the water reach thermal equilibrium, they have same temperature, $T=58.5^{\circ}C$ .
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The hear released by the water is:
$Q_w =m_w C_{sw} \Delta T_w$
where $m_w$ is the water mass, $C_{sw}=4.186 J/(g^{\circ}C)$ is the specific heat of the water, and $\Delta T_w = 63.6^{\circ}-58.5^{\circ}=5.1^{\circ}C$ is the variation of temperature of the water.

Similarly, the heat absorbed by the iron is:
$Q_i = m_i C_{si} \Delta T_i$
where $m_i = 33.0 g$ is the iron mass, $C_{si}=0.444 J/(g^{\circ}C)$ is the iron specific heat, and $\Delta T_i = 58.5^{\circ}-22.7^{\circ}=35.8^{\circ}C$ is the variation of temperature of the iron.

Writing $Q_w=Q_i$ and replacing the numbers, we can solve to find mw, the mass of the water:
$m_w= \frac{m_i C_{si} \Delta T_i}{C_{sw} \Delta T_w} =24.6 g$

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4 years ago