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frutty [35]
3 years ago
5

A certain sprinter has a top speed of 10.5 m/s. If the sprinter starts from rest and accelerates at a constant rate, he is able

to reach his top speed in a distance of 12.0 m. He is then able to maintain his top speed for the remainder of a 100 m race. (a) What is his time for the 100 m race
Physics
1 answer:
Svet_ta [14]3 years ago
4 0

Answer:

Total time = 10.667 seconds

Explanation:

For the first 12m

V² = u² + 2as

10.5² = 0² + 2a(12)

110.25 = 24a

a = 4.59375 m/s²

V = u + at

10.5 = 0 + 4.59375t

t = 10.5/4.59375

t = 2.286 seconds

For the remaining race

100-12 = 88m

He travels at a constant speed for 88m

S = ut + 1/2(at²)

But a = 0

S = ut

88= 10.5t

t = 88/10.5

t = 8.38.seconds

Total time = 2.286 + 8.381

Total time = 10.667 seconds

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Virty [35]

Answer:

Energy transferred = 28.8 Joules.

1. Energy transferred = 144 Joules.

2. The unit of potential difference, volts can also be described as Joules per Coulombs.

3. Current, I = 6.945 Amperes.  

Explanation:

<u>Part A.</u>

Given the following data;

Current, I = 1.2A

Time, t = 2 minutes

Potential difference, V = 12 volts.

To find the energy transfered;

Energy transferred = charge moved * potential difference

E = Q * V

Substituting into the equation, we have;

Energy transferred = (1.2 * 2) * 12

Energy transferred = 2.4 * 12

Energy transferred = 28.8 Joules.

<u>Part B.</u>

1. <em><u>Given the following data;</u></em>

Charge, Q = 24C

Potential difference = 6V

To find the energy transferred;

E = Q * V

Substituting into the equation, we have;

E = 24 * 6

E = 144 Joules.

2. Since we know that, Energy transferred = charge moved * potential difference

Potential \; difference = \frac {Energy \; transferred}{Charged \; moved}

The units of energy is Joules while the unit of the quantity of charge moved is Coulomb.

Therefore, the unit of potential difference becomes Joules per Coulomb.

3. <em><u>Given the following data;</u></em>

Potential difference = 18V

Energy transferred = 500J

Time, t = 4 minutes.

To find the current;

E = Q * V

Substituting into the equation, we have;

500 = Q*18

Q = 500/18

Q = 27.78C

But, Charge moved (Q) = current (I) * time (t)

Current, I = Q/t

Substituting into the equation, we have;

Current, I = 27.78/4

Current, I = 6.945 Amperes..

3 0
3 years ago
When a 2.50 kg object is hung vertically on a certain light spring described by hookes law the spring stretches 2.76 cm.
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F=K*X,
F=M*a 

M*a=K*X

2.5*9.81=K*0.0276

24.525=K*0.0276

24.525/0.0276=K

K= 888.6 N/m ---- force constant 

assuming 2.5 refers to the new extension, just divide F/ 0.025
to get

981N/m 


8 0
3 years ago
A cubical block of wood, 10.0 cm on a side, floats at the interface between oil and water with its lower surface 1.50 cm below t
bezimeni [28]

Answer:

the gauge pressure at the upper face of the block is 116 Pa

Explanation:

Given the data in the question;

A cubical block of wood, 10.0 cm on a side.

height h = 1.50 cm = ( 1.50 × ( 1 / 100 ) ) m = 0.0150 m

density ρ = 790 kg/m³

Using expression for the gauged pressure;

p-p₀ = ρgh

where, p₀ is atmospheric pressure, ρ is the density of the substance, g is acceleration due to gravity and h is the depth of the fluid.

we know that, acceleration due to gravity g = 9.8 m/s²

so we substitute

p-p₀ = 790 kg/m³gh × 9.8 m/s² × 0.0150 m

= 116.13 ≈ 116 Pa

Therefore, the gauge pressure at the upper face of the block is 116 Pa

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To solve this problem it is necessary to use the concepts related to the Hall Effect and Drift velocity, that is, at the speed that an electron reaches due to a magnetic field.

The drift velocity is given by the equation:

V_d = \frac{I}{nAq}

Where

I = current

n = Number of free electrons

A = Cross-Section Area

q = charge of proton

Our values are given by,

I = 25 A

A= 1.2*20 *10^{-6} m^2

q= 1.6*10^{-19}C

N = 8.47*10^{19} mm^{-3}

V_d =\frac{25}{(1.2*20 *10^{-6})(1.6*10^{-19})(8.47*10^{19} )}

V_d = 7.68*10^{-5}m/s

The hall voltage is given by

V=\frac{IB}{ned}

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e = charge of electron

Then using the formula and replacing,

V=\frac{(2.5)(25)}{(8.47*10^{28})(1.6*10^{-19})(1.2*10^{-3})}

V = 3.84*10^{-6}V

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3 years ago
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