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3 years ago

How many seconds of space should you keep between you if you're driving a 100 foot truck 30 mph?

Physics

1 answer:

Marrrta [24]3 years ago

7 0

Answer:

 The space in seconds that will be kept = 2.27 seconds

Explanation:

S = d/t..................... Equation 1

making t the subject of formula in the equation above,

t = d/S.................... Equation 2

Where S = speed, d = distance, t = time.

Conversion: (i)if 1 mph = 0.44704 m/s,

then, 30 mph = 30×0.44704

= 13.41 m/s

(ii) If 1 foot = 0.3048 m

then, 100 foot = 30.48 m.

Given: S = 30 mph = 13.41 m/s, d = 100 foot = 30.48 m

Substituting these values into equation 2

t = 30.48/13.41

t = 2.27 seconds.

Therefore the space in seconds that will be kept = 2.27 seconds

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Describe an environment in which the sound of a ringing cell phone could not be transmitted, and explain why the ringing wouldn'

Sveta_85 [38]

Answer:

In a vacuum

Explanation:

Sound is a type of mechanical waves. Mechanical waves are waves that propagate through the oscillation of the particles in a medium, which can be either gas, liquid or solid.

A sound wave in air, for instance, is simply produced by the oscillations of the air particles back and forth along the direction of motion of the wave.

Given this definition, it is clear that mechanical waves (and so, sound waves as well) cannot be transmitted if there is no medium: therefore, they cannot be transmitted in a vacuum. So, the sound of the ringing bell would not be present in a vacuum.

8 0

3 years ago

A 2000 kg car moving at 100 km/h crosses the top of a hill with a radius of curvature of 100 m. What is the normal force exerted

Tpy6a [65]

Answer:

The normal force the seat exerted on the driver is 125 N.

Explanation:

Given;

mass of the car, m = 2000 kg

speed of the car, u = 100 km/h = 27.78 m/s

radius of curvature of the hill, r = 100 m

mass of the driver, = 60 kg

The centripetal force of the driver at top of the hill is given as;

$F_c = F_g - F_N$

where;

Fc is the centripetal force

$F_g$ is downward force due to weight of the driver

$F_N$ is upward or normal force on the drive

$F_N = F_g-F_c\\\\F_N = mg - \frac{mv^2}{r} \\\\F_N = (60 \times 9.8) -\frac{60 \ \times \ 27.78^2 \ }{100} \\\\F_N = 588 \ N - 463 \ N\\\\F_N = 125 \ N$

Therefore, the normal force the seat exerted on the driver is 125 N.

6 0

2 years ago

If an airplane is flying directly north at 300.0 km/h, and a crosswind is hitting the airplane at 50.0 km/h from the east, what

Rashid [163]

Answer:

magnitude = 304.14 km/h

direction: $9.46^o$ West of North

Explanation:

The final plane's vector velocity will be the result of the vector addition of one pointing North of length 300 km/h, another one pointing West of length 50 km/h.

To find the magnitude of the final velocity vector (speed) we need to apply the Pythagorean theorem in a right angle triangle with sides: 300 and 50, and find its hypotenuse:

$|v|=\sqrt{300^2+50^2}=\sqrt{92500} = 304.14$ km/h

The actual direction of the plane is calculated using trigonometry, in particular with the arctan function, since the tangent of the angle can be written as:

$tan(\theta)=\frac{50}{300} = \frac{1}{6} \\\theta = arctan(\frac{1}{6} ) = 9.46^o$

So the resultant velocity vector of the plane has magnitude = 304.14 km/h,

and it points $9.46^o$ West of the North direction.

3 0

3 years ago

A wire is made from a material having a temperature coefficient of resistivity of 0.0003125 (°C^-1). In an experiment, we mainta

beks73 [17]

Answer:

The power decreases by 36%

Explanation:

Given:

At 20° C

Power, P₀ = 300 W

Potential difference, V = 150 volts

Now, power is given as

P = V²/R

where, R is the resistance

on substituting the values, we get

300 = 150²/R₀

R₀ = 75 Ω

Now, the variation of resistance with temperature is given as

R = R₀[1 + α(T - T₀)]

where, α is the temperature coefficient of resistivity = 0.0003125 (°C⁻¹)

now, at

T₀ = 20° C

R₀ = 75 Ω

for

T = 1820° C

we have

R = R₀[1 + α(T - T₀)]

substituting the values

we get

R = 75×[1 + 0.0003125 × (1820 - 20)]

R = 117.18 Ω

Now using the formula for power

We have,

P = V²/R

P = 150²/117.18 = 192 W

Therefore, the percentage change will be

= $\frac{P-P_0}{P_0}\times 100$

on substituting the values , we get

= $\frac{192-300}{300}\times 100$

= -36%

here, negative sign depicts the decrease in power

3 0

3 years ago

Read 2 more answers

A certain metal wire has a cross sectional area of 1 mm2 and is 1 m long. when it is hung from the ceiling and a 10 kg mass is h

kvasek [131]

From the Hooke's law , the extension force of an elastic material is directly proportional to the extension.
That is, F = k e, where F is the force , k is the constant and e is the extension
F = 10 × 10 = 100 N
e = 1mm or 0.001 m
Hence, k = F/e
= 100 N/ 0.001
= 100000 N/m or 100 N/mm

5 0

3 years ago