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natulia [17]
3 years ago
6

a ball was 2.0 m off the ground and thrown horizontally. it traveled for 7.8 m before it hit the ground. what was the imitial sp

eed of the ball
Physics
1 answer:
Leto [7]3 years ago
7 0

Answer:

12 m/s

Explanation:

First, find the time it takes for the ball to fall 2.0 m.

y = y₀ + v₀ t + ½ at²

0 = 2.0 + (0) t + ½ (-9.8) t²

0 = 2 − 4.9t²

t = 0.639

Find the velocity needed to travel 7.8 m in that time.

x = x₀ + v₀ t + ½ at²

7.8 = 0 + v₀ (0.639) + ½ (0) (0.639)²

7.8 = 0.639 v₀

v₀ = 12.2

Rounded to two significant figures, the initial velocity is 12 m/s.

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A if two such generic humans each carried 2.5 coulomb of excess charge, one positive and one negative, how far apart would they
dolphi86 [110]

Using Coulomb's Law <span>

F = {k(Q1)(Q2)}/r² 

Where F =force in Newtons, k = Coulomb constant, Q1 = - Q2= charge of the objects in Coulumbs, and r is the distance between the objects. 

Solving for r: 

r = sqrt[{k(Q1)(Q2)}/F] 

where k = 8.897 x 10^9 N•m²/C², Q1 = 2.5 C, Q2 = -2.5 C, and F = -700 N 

Note: Negative magnitude of Force indicates attraction. 

<span>r = 8,912.77 m</span></span>

3 0
4 years ago
Name some devices we use to make measurements
NikAS [45]

Answer:

Explanation:

Ruler. A steel ruler aids the measurement and layout of straight lines. The ruler, also called "straightedge" or "straight-edged ruler," is a long, thin strip of wood, metal or plastic marked with increments of measurement.

Measuring Tape. The modern measuring tape's roughly palm-sized casing contains a coiled strip of metal marked with increments of measurement. The metal strip, called "tape," attaches to a spring which automatically retracts the tape into the casing following use.

Walking Tape Measure. The walking tape measure, also called "surveyor's measure," records the distance traveled by a wheel. An operator pushes the measure's wheel, similar to a bicycle wheel, by a handle as an attached ticker box displays feet or meters in the same format as a car's odometer.

Laser Measure. The laser measure offers point and shoot distance measurement. In its most basic form, a laser measure is a hand-held electronic device with a digital display.

4 0
3 years ago
Find the resistance of an electric light bulb if a current of 0.08 A flows when the potential difference across the bulb is 120
lora16 [44]
U=RI Ohm's law
then R=U/I
=120/0.08
=2250Ω
hope this helps you
8 0
3 years ago
A 400-kg box is lifted vertically upward with constant velocity by means of two cables pulling at 40.0° on either side of the ve
iren2701 [21]

Answer:

Tension, T = 2558.59 N

Explanation:

It is given that,

Mass of the box, m = 400 kg

The box is lifted vertically upward with constant velocity by means of two cables pulling at 40 degrees on either side of the vertical direction. Since, the cables are symmetrical. So, tension will be same on each cable.

2T\ cos\theta=mg

T=\dfrac{mg}{2cos\theta}

T=\dfrac{400\times 9.8}{2\times cos(40)}

T = 2558.59 N

So, the tension in each cable is 2558.59 N. Hence, this is the required solution.

3 0
3 years ago
A dentist's drill starts from rest. After 3.00 s of constant angular acceleration it turns at a rate of 2.60 x 104 rev/min (a) F
Vikentia [17]

Answer:

(a)

907.11 rad/s²

(b)

4082 rad

Explanation:

(a)

t = time taken = 3.00 s

w₀ = initial angular velocity of the drill = 0 rad/s

w = final angular velocity of the drill = 26000 rev/min = 26000 \frac{rev}{min}\frac{6.28rad}{1 rev}\frac{1 min}{60 sec} = 2721.33 rad/s

α = angular acceleration of the drill

t = time interval = 3.00 s

using the equation

w = w₀ + α t

2721.33 = 0 + α (3)

α = 907.11 rad/s²

(b)

θ = angle

using the equation

θ = w₀ t + (0.5) α t²

θ = (0) (3.00) + (0.5) (907.11) (3.00)²

θ = 4082 rad

5 0
4 years ago
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