Is the value of resistance the same for all materials?

If the sprinter from the previous problem accelerates at that rate for 20 m, and then maintains that velocity for the remainder

kakasveta [241]

Question:

A 63.0 kg sprinter starts a race with an acceleration of 4.20m/s square. What is the net external force on him? If the sprinter from the previous problem accelerates at that rate for 20m, and then maintains that velocity for the remainder for the 100-m dash, what will be his time for the race?

Answer:

Time for the race will be t = 9.26 s

Explanation:

Given data:

As the sprinter starts the race so initial velocity = v₁ = 0

Distance = s₁ = 20 m

Acceleration = a = 4.20 ms⁻²

Distance = s₂ = 100 m

We first need to find the final velocity (v₂) of sprinter at the end of the first 20 meters.

Using 3rd equation of motion

(v₂)² - (v₁)² = 2as₁ = 2(4.2)(20)

v₂ = 12.96 ms⁻¹

Time for 20 m distance = t₁ = (v₂ - v ₁)/a

t₁ = 12.96/4.2 = 3.09 s

He ran the rest of the race at this velocity (12.96 m/s). Since has had already covered 20 meters, he has to cover 80 meters more to complete the 100 meter dash. So the time required to cover the 80 meters will be

Time for 100 m distance = t₂ = s₂/v₂

t₂ = 80/12.96 = 6.17 s

Total time = T = t₁ + t₂ = 3.09 + 6.17 = 9.26 s

T = 9.26 s

5 0

3 years ago

An electric field of 1.27 kV/m and a magnetic field of 0.490 T act on a moving electron to produce no net force. If the fields a

lesantik [10]

Answer:

v = 2591.83 m/s

Explanation:

Given that,

The electric field is 1.27 kV/m and the magnetic field is 0.49 T. We need to find the electron's speed if the fields are perpendicular to each other. The magnetic force is balanced by the electric force such that,

$qE=qvB\\\\v=\dfrac{E}{B}\\\\v=\dfrac{1.27\times 10^3}{0.49}\\\\v=2591.83\ m/s$

So, the speed of the electron is 2591.83 m/s.

8 0

3 years ago

A spring with a constant of 92N/m is compressed 2.8 cm. How much potential energy is stored in the spring?

Arada [10]

Answer:

0.036J

Explanation:

Given parameters:

Spring constant , K = 92N/m

Compression = 2.8cm = 0.028m

Unknown:

Potential energy = ?

Solution:

To solve this problem;

P.E = $\frac{1}{2}$ K e²

K is the spring constant

e is the compression

so;

P.E = $\frac{1}{2}$ x 92 x 0.028² = 0.036J

6 0

3 years ago

Why do we have thunder storms

Over [174]

Thunderstorms happen when cold air sinks and hot air rises in rapid succession. There has to be an unstable body of hot air for a thunderstorm to happen. Cool air mingles with the hot air causing condensation (that means that raindrops form) This makes a cumulous cloud.
The moisture in the cloud is either positively charged or negatively charged. Negatively charged particles sink to the bottom of the cumulous cloud while positively charges particles rise. The positive and negative charges rub together and spark causing lightning.
Thunder is formed by the lightning, a bolt of lightning is hollow, and has no air inside it. When the lightning dissipates the air rushes to fill the space breaking the sound barrier in the process, this creates the boom.

3 0

3 years ago

If an ocean wave passes a stationary point every 5 s and has a velocity of 10 m/s, what is the wavelength of the wave

Rainbow [258]

Answer:

As Per Provided Information

Velocity of wave v is 10m/s

These ocean wave passes a stationary point every 5 s ( It's time period)

First we calculate the frequency of ocean wave .

Using Formulae

$\blue{\boxed{\bf \: \nu = \cfrac{1}{v}}}$

here

v is the velocity of wave .

$\sf\longrightarrow \nu \: = \cfrac{1}{10} \\ \\ \\ \sf\longrightarrow \nu \: = 0.1Hz$

Now calculating the wavelength of the wave .

Using Formulae 

$\boxed{ \bf \lambda = \cfrac{v}{ \nu}}$

Substituting the value and we obtain

$\sf \longrightarrow \lambda \: = \cfrac{10}{0.1} \\ \\ \\ \sf \longrightarrow \lambda \: = \cancel\cfrac{10}{0.1} \\ \\ \\ \sf \longrightarrow \lambda \: =100m$

Therefore,

Wavelength of the wave is 100 metres.

8 0

3 years ago

Is the value of resistance the same for all materials?​

Is the value of resistance the same for all materials?