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3 years ago

4. Brandon throws a tennis ball vertically upward. The ball returns to the point of release after 4.0 s. What is the

Physics

1 answer:

vekshin13 years ago

6 0

Answer:

-39.2m/s

Explanation:

Using the equation of motion;

v = u + at

Since the ball is thrown upward, the acceleration due to gravity acting on it will be negative, hence a = -g

v = u - gt

Since g = 9.8m/s²

t = 4.0s

u = 0m/s

v = 0 + (-9.8)(4)

v = -39.2m/s

Hence the speed of the ball before release is -39.2m/s

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In the equation for centripetal force, which expression represents the centripetal acceleration of the object? mv2 StartFraction

Sphinxa [80]

Answer: $\frac{V^{2}}{r}$

Explanation:

According to Newton's 2nd Law of motion the force $F$ is proportional to the mass $Fm$ and acceleration $a$ :

$F=m.a$ (1)

On the other hand, the equation for the Centripetal force is:

$F=\frac{mV^{2}}{r}$ (2)

Where:

$V$ is the velocity

$r$ is the radius of the circular motion

Making (1) and (2) equal:

$m.a=\frac{mV^{2}}{r}$ (3)

Hence:

$a=\frac{V^{2}}{r}$ This is the expression for the centripetal acceleration

It should be noted, this acceleration is directed toward the center of the circumference of the circular motion (that's why it's called centripetal acceleration).

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3 years ago

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Choose all of the true statements regarding the relationship between voltage, resistance, and current. Current is measured in am

AveGali [126]

-- Current is measured in amps. (You can use any symbol you want to represent current, but the most common one is " I ", not "Δ".)

-- The relationship between current, voltage, and resistance is mathematically defined by Ohm's Law.

-- Current is the flow of electrons through a circuit.

-- (Ohm's Law is NOT mathematically represented by the equation V=I/R.) It should be V = I · R .

(When solving for Resistance in a circuit and both voltage and current are known values, the equation I =V*R is not true, and not the way to solve it.) If the resistance is what you're looking for, then the equation to use is R = V / I .

-- If the voltage in a circuit is increased, the current will also increase.

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3 years ago

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What is the area of a rectangle whose sides are 3.2 m and 8.01 m? Answer in units of m²

alexgriva [62]

Answer:

25.632 m²

Explanation:

area = a*b

area = 3.2m * 8.01m

area = 25.632 m²

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3 years ago

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What is the resistance of a bulb of 4ow connected in a line of 220v? 2

inn [45]

Answer:

1210 ohm

Explanation:

Given :

P=40 W

V=220 V

Now,

$P=\frac{V^{2} }{R} \\40=\frac{(220)^{2} }{R} \\40R=48400\\R=\frac{48400}{40} \\R=1210 ohm$

Therefore, resistance of bulb will be 1210 ohm

8 0

3 years ago

It is claimed that if a lead bullet goes fast enough, it can melt completely when it comes to a halt suddenly, and all its kinet

Amiraneli [1.4K]

Answer:

354.72 m/s

Explanation:

$m$ = mass of lead bullet

$c$ = specific heat of lead = 128 J/(kg °C)

$L$ = Latent heat of fusion of lead = 24500 J/kg

$T_{i}$ = initial temperature = 27.4 °C

$T_{f}$ = final temperature = melting point of lead = 327.5 °C

$v$ = Speed of lead bullet

Using conservation of energy

Kinetic energy of bullet = Heat required for change of temperature + Heat of melting

$(0.5) m v^{2} = m c (T_{f} - T_{i}) + m L\\(0.5) v^{2} = c (T_{f} - T_{i}) + L\\(0.5) v^{2} = (128) (327.5 - 27.4) + 24500\\(0.5) v^{2} = 62912.8\\v = 354.72 ms^{-1}$

3 0

3 years ago