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astraxan [27]
3 years ago
8

If a car has an initial velocity of 20 m/s and accelerates at 2.0 m/s² for 100 m, what is its final velocity?

Physics
1 answer:
WINSTONCH [101]3 years ago
8 0

Answer:

28.28 ms-1

Explanation:

v² = u² + 2as

v² = 20² + 2× 2×100

v² = 800

v = 28.28 ms-1

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A ball is dropped from rest at point O . It passes a window with height 3.8 m in time interval tAB = 0.02 s.Identify the correct
Taya2010 [7]

Answer:

VB − VA = g tAB   &   (VA + VB)/2 = h / tAB

Explanation:

s = h = Displacement

tAB = t = Time taken

VA = u = Initial velocity

VB = v = Final velocity

a = g = Acceleration due to gravity = 9.8 m/s²

s=ut+\frac{1}{2}at^2\\\Rightarrow u=\frac{s-\frac{1}{2}at^2}{t}\\\Rightarrow u=\frac{3.8-\frac{1}{2}\times 9.8\times 0.02^2}{0.02}\\\Rightarrow u=189.902\ m/s

v=u+at\\\Rightarrow v=189.902+9.8\times 0.02\\\Rightarrow v=190.098\ m/s

\frac{v+u}{2}=\frac{190.098+189.902}{2}=190\ s

\frac{h}{t}=\frac{3.8}{0.02}=190\ s

Hence, the equations VB − VA = g tAB   &   (VA + VB)/2 = h / tAB will be used

3 0
3 years ago
A string is attached to a ball that has a mass of 0.11 kg. A student pulls up on the string so that the ball accelerates upward
enot [183]

Answer:

T=+1.133N

Explanation:

Tension and weight are forces that have opposite directions

Weight is negative (downward)

W=m*g= 0.11kg*(-9.8m/s^2)

W= -1.078N

Tension is possitive (upward)

The total force will be the sum of both (the difference taking in consideration the direction)

Ft= T+W

Also the total force is the product of the mass due to acceleration:

Ft=m*a

Ft= +0.11kg*0.5m/s^2

Ft=+0.055N (upward)

Tension will be the difference between Ft and W:

T= Ft-W

T=+0.055N-(-1.078N)

T=+1.133N

7 0
3 years ago
Describe how the number of photoelectrons emitted from a metal plate in the photoelectric effect would change if the following o
andrew-mc [135]

Answer:

a) True. The number of photoelectrons is proportional to the amount (intensity) of the incident beam. From the expression above we see that threshold frequency cannot emit electrons.

b)   λ = c / f

Therefore, as the wavelength increases, the frequency decreases and therefore the energy of the photoelectrons emitted,

c)  threshold energy

        h f =Ф

Explanation:

It's photoelectric effect was fully explained by Einstein by the expression

       Knox = h f - fi

Where K is the kinetic energy of the photoelectrons, f the frequency of the incident radiation and fi the work function of the metal

a) True. The number of photoelectrons is proportional to the amount (intensity) of the incident beam. From the expression above we see that threshold frequency cannot emit electrons.

b) wavelength is related to frequency

         λ = c / f

Therefore, as the wavelength increases, the frequency decreases and therefore the energy of the photoelectrons emitted, so there is a wavelength from which electrons cannot be removed from the metal.

c) As the work increases, more frequency radiation is needed to remove the electrons, because there is a threshold energy

        h f =Ф

7 0
3 years ago
Two spacemen are floating together with zero speed in a gravity-free region of space. The mass of spaceman A is 120 kg and that
maw [93]

Answer:

your answer is A

Explanation:

4 0
3 years ago
An ideal battery would produce an extraordinarily large current if "shorted" by connecting the positive and negative terminals w
liubo4ka [24]

Answer:

Resistance, R=0.529\ \Omega

Explanation:

Given that,

Voltage of the battery, V = 9 volts

Current produced in the circuit, I = 17 A

We need to find the resistance when shorted by a wire of negligible resistance. It is a case of Ohm's law. The voltage is given by :

V=IR

R=\dfrac{V}{I}

R=\dfrac{9\ V}{17\ A}

R=0.529\ \Omega

So, the resistance in the circuit is 0.529 ohms. Hence, this is the required solution.

6 0
3 years ago
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