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An object is dropped from a platform 100 feet high. Ignoring wind resistance, what will its speed be when it reaches the ground?

ICE Princess25 [194]

if we assume the origin is at the dropping point and the object is merely dropped and not thrown up or down then y0 = 0 and v0 = 0. The equation reduces to 

y = 0 + 0t + ½gt² 
y = ½gt² 

t = √(2y/g) 

in the ft - lb - s system 

y = -100 ft 
g = -32.2 ft / s² 

t = √(2y/g) 
t = √(2(-100) / (-32.2)) 
t = 2.5 s

7 0

3 years ago

Read 2 more answers

What are the names of the 2 charged particles in an atom and what are their charges

Sholpan [36]

Answer:

Protons and electrons

Explanation:

The atoms are made up of protons, neutrons, and electrons.
The physical and chemical characteristics of an atom are determined by the number of these particle composition.
The protons present in the center of an atom called the nucleus is positively charged.
The neutrons are also located in the nucleus of an atom with no charge.
The electrons has a negative charge and it is placed around the nucleus having different shells and quantum state.
The charges of the protons and electrons are denoted by +q and -q. The quantization of these charges are +1, +2, ... and -1, -2, .... etc.

3 0

2 years ago

Give an example of a Claim.

Olin [163]

Answer:

Yeah

Explanation:

Look at the pic!!

5 0

2 years ago

Potassium is a crucial element for the healthy operation of the human body. Potassium occurs naturally in our environment and th

Mariulka [41]

Answer:

a) 0.0288 grams

b) $2.6*10^{-10} J/kg$

Explanation:

Given that:

A typical human body contains about 3.0 grams of Potassium per kilogram of body mass

The abundance for the three isotopes are:

Potassium-39, Potassium-40, and Potassium-41 with abundances are 93.26%, 0.012% and 6.728% respectively.

a)

Thus; a person with a mass of 80 kg will posses = 80 × 3 = 240 grams of potassium.

However, the amount of potassium that is present in such person is :

0.012% × 240 grams

= 0.012/100 × 240 grams

= 0.0288 grams

b)

the effective dose (in Sieverts) per year due to Potassium-40 in an 80- kg body is calculate as follows:

First the Dose in (Gy) = $\frac{energy \ absorbed }{mass \ of \ the \ body}$

= $\frac{1.10*10^6*1.6*10^{-14}}{80}$

= $2.2*10^{-10} \ J/kg$

Effective dose (Sv) = RBE × Dose in Gy

Effective dose (Sv) = $1.2 *2.2*10^{-10} \ J/kg$

Effective dose (Sv) = $2.6*10^{-10} J/kg$

5 0

2 years ago

A stone is thrown straight downward with a speed of 20 m/s from the top of a tall building. If the stone strikes the ground 3.0

Lady_Fox [76]

Do you remember this formula for the distance traveled while accelerated ?

Distance = (initial speed) x (t) plus (1/2) x (acceleration) x (t²)

I think this is exactly what we need for this problem.

initial speed = 20 m/s down
acceleration = 9.81 m/s² down
t = 3.0 seconds

Distance down = (20) x (3) plus (1/2) x (9.81) x (3)²

Distance = (60) plus (4.905) x (9)

Distance = (60) plus (44.145) = 104.145 meters

Choice D) is the closest one.

6 0

2 years ago