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3 years ago

HELP PLEASE!!! I'M REALLY BAD AT MECHANICAL ENERGY!!!

Physics

1 answer:

deff fn [24]3 years ago

7 0

Kinetic is something moving and potential is being still

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A boy is using a rope to pull a sled to the left on a horizontal surface. The rope is parallel to the surface. What are the dire

trasher [3.6K]

Answer:

Explanation:

Check attachment

3 0

4 years ago

Iodine 131 half life is 8.0 days. Ten percent of the original sample o his isotope remains after (a) 22.7 days (b) 24.9 days (c)

Artyom0805 [142]

Answer:

option (c) is correct

Explanation:

Half life of a substance is the time in which the element becomes half of is initial value.

half life, T = 8 days

Amount remaining, N = 10 % of original value

Let the original value is No.

N = 10% of No

N = 0.1 No

Let the time taken is t and the decay constant is λ.

The relation between the decay constant and the half life is given by

$\lambda =\frac{0.6931}{T}=\frac{0.6931}{8}=0.08664 per day$

Us the equation of radioactivity

$N=N_{0}e^{-\lambda t}$

$0.1N_{0}=N_{0}e^{-0.08664 t}$

$e^{0.08664 t}=10$

Taking natural log on both the sides, we get

0.08664 t = 2.303

t = 26.6 days

4 0

3 years ago

Can anybody tell me the right answer ? please and thank you !!

ad-work [718]

Answer:

c. selenium

Explanation:

sulfur and selenium are in the same group

3 0

3 years ago

A 234.0 g piece of lead is heated to 86.0oC and then dropped into a calorimeter containing 611.0 g of water that initally is at

Vaselesa [24]

Answer: $24.70 ^{\circ}C$

Explanation:

Given

mass of lead piece $m_l=234 gm\approx 0.234 kg$

mass of water in calorimeter $m_w=611 gm\approx 0.611 kg$

Initial temperature of water $T_w=24^{\circ}C$

Initial temperature of lead piece $T_l=24^{\circ}C$

we know heat capacity of lead and water are $125.604 J/kg-k$ and $4.184 kJ/kg-k$ respectively

Let us take $T ^{\circ}C$ be the final temperature of the system

Conserving energy

heat lost by lead=heat gained by water

$m_lc_l(T_l-T)=m_wc_w(T-T_w)$

$0.234\times 125.604(86-T)=0.611\times 4.184\times 1000(T-24)$

$86-T=\frac{0.611\times 4.184\times 1000}{29.391}(T-24)$

$86-T=86.97T-2087.49$

$T=\frac{2173.491}{87.97}=24.70^{\circ}C$

3 0

3 years ago

A firewoman dropped a person onto the safety net. Right before the person hit the net he had a

sergejj [24]

Answer:

The Mass of a person is calculated to be 28.6kg .

Explanation:

This is based on Kinetic energy and we know, that Kinetic energy is the energy possessed by body by virtue of its motion .

It can be calculated by expression :

K.E=1/2mv²

Velocity of a person = 11.2m/sec

Kinetic energy = 1800J

Mass of person = ?

We know ,

K.E=1/2mv²

so, putting values we have :

1800=1/2 x m x (11.2)²

That is ,

m=1800 x 2 /11.2 x 11.2

m=3600/125.44

m = 28.6 kg

6 0

3 years ago