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Daniel [21]
3 years ago
5

You throw a ball upward with an initial speed of 4.3 m/s. When it returns to your hand 0.88 s later, it has the same speed in th

e downward direction (assuming air resistance can be ignored). What was the average acceleration vector of the ball? Express your answer using two significant figures.
Physics
1 answer:
djverab [1.8K]3 years ago
4 0

Answer:

The acceleration is -9.8 m/s²

Explanation:

Hi there!!

When you throw a ball upward, there is a downward acceleration that makes the ball return to your hand. This acceleration is produced by gravity.

The average acceleration is calculated as the variation of the speed over time. In this case, we know the time and the initial and final speed. Then:

acceleration = final speed - initial speed/ elapsed time

acceleration = -4.3 m/s - 4.3 m/s / 0.88 s

acceleration = -9.8 m/s²  

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Space-faring astronauts cannot use standard weight scales (since they are constantly in free fall) so instead they determine the
valentinak56 [21]

Answer:

ma = 48.48kg

Explanation:

To find the mass of the astronaut, you first calculate the mass of the chair by using the information about the period of oscillation of the empty chair and the spring constant. You use the following formula:

T=2\pi\sqrt{\frac{m_c}{k}}     (1)

mc: mass of the chair

k: spring constant = 600N/m

T: period of oscillation of the chair = 0.9s

You solve the equation (1) for mc, and then you replace the values of the other parameters:

m_c=\frac{T^2k}{4\pi^2}=\frac{(0.9s)^2(600N/m)}{4\pi^2}=12.31kg    (2)

Next, you calculate the mass of the chair and astronaut by using the information about the period of the chair when the astronaut is sitting on the chair:

T': period of chair when the astronaut is sitting = 2.0s

M: mass of the astronaut plus mass of the chair = ?

T'=2\pi\sqrt{\frac{M}{k}}\\\\M=\frac{T'^2k}{4\pi^2}=\frac{(2.0s)^2(600N/m)}{4\pi^2}\\\\M=60.79kg (3)

Finally, the mass of the astronaut is the difference between M and mc (results from (2) and (3)) :

m_a=M-m_c=60.79kg-12.31kg=48.48kg

The mass of the astronaut is 48.48 kg

3 0
3 years ago
A human being can be electrocuted if a current as small as 51.0 ma passes near the heart. an electrician working with sweaty han
boyakko [2]

The fatal current is 51 mA = 0.051 Ampere.

The resistance is 2,050Ω .

Voltage = (current) x (resistance)

            =  (0.051 Ampere) x (2,050 Ω)  =  104.6 volts .

==================

This is what the arithmetic says IF the information in the question
is correct.

I don't know how true this is, and I certainly don't plan to test it,
but I have read that a current as small as  15 mA  through the
heart can be fatal, not  51 mA .

If 15 mA can do it, and the sweaty electrician's resistance is
really 2,050 Ω, then the fatal voltage could be as little as  31 volts !

The voltage at the wall-outlets in your house is  120 volts in the USA !
THAT's why you don't want to stick paper clips or a screwdriver into
outlets, and why you want to cover unused outlets with plastic plugs
if there are babies crawling around.
6 0
3 years ago
During a circus act, an elderly performer thrills the crowd by catching a cannon ball shot at him. The cannon ball has a mass of
Ipatiy [6.2K]

Answer:

m v1 = (m + M) v2

v2 = m v1 / (m + M)

v2 = 7 * 74 / (74 + 65)

3.73 m/s

74 kg is too heavy for the cannonball (over 150 lbs)

4 0
3 years ago
An hydrogen molecule consists of two hydrogen atoms whose total mass is 3.3×10−27 kg and whose moment of inertia about an axis p
dlinn [17]

Answer:

6.9631\times 10^{-11}\ m

Explanation:

I = Moment of inertia = 4\times 10^{-48}\ kg m^2

m = Mass of two atoms = 2m = 3.3\times 10^{-27}\ kg

r  = distance between axis and rotation mass

Moment of inertia of the system is given by

I=mr^2\\\Rightarrow I=2mr^2\\\Rightarrow 4\times 10^{-48}=3.3\times 10^{-27}\times r^2\\\Rightarrow r=\sqrt{\frac{4\times 10^{-48}}{3.3\times 10^{-27}}}\\\Rightarrow r=3.48155\times 10^{-11}\ m

The distance between the atoms will be two times the distance between axis and rotation mass.

d=2r\\\Rightarrow d=2\times 3.48155\times 10^{-11}\\\Rightarrow d=6.9631\times 10^{-11}\ m

Therefore, the distance between the two atoms is 6.9631\times 10^{-11}\ m

3 0
3 years ago
At what distance from the centre of the earth its acceleration due to gravity becomes one third only? [Mass and radius of earth
Kipish [7]

Answer:

235

Explanation:

3 0
3 years ago
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