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3 years ago

Which is something that a vacuum tube cannot do?

Physics

2 answers:

Oxana [17]3 years ago

8 0

D) concert electrical energy into thermal energy

Butoxors [25]3 years ago

4 0

Answer:

Explanation:

A vacuum tube is a glass tube that creates the conditions of a vacuum to allow for electric current to pass through it.

Originally, vacuum tubes were used in electronics to amplify electric signals, however, today they have been replaced by more efficient systems, such as transistors.

A vacuum tube can change alternating current into direct current, it can turn a current on or off, and as stated above, it can increase the signal strength. However, it cannot change electrical energy into thermal energy, and that is why the answer is D.

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What is cheetah speed and strength?

pav-90 [236]

Answer:

Speed: 109.4–120.7 km/h (68.0–75.0 mph)

Strength: Couldn't find out.

Explanation:

3 0

3 years ago

A sprinter in a 100-m race accelerates uniformly for the first 71 m and then runs with constant velocity. The sprinter’s time fo

adoni [48]

Answer:

The acceleration of the sprinter is 1.4 m/s²

Explanation:

Hi there!

The equation of position of the sprinter is the following:

x = x0 + v0 · t + 1/2 · a · t²

Where:

x = position of the sprinter at a time t.

x0 = initial position.

v0 = initial velocity.

t = time.

a = acceleration.

Since the origin of the frame of reference is located at the starting point and the sprinter starts from rest, then, x0 and v0 are equal to zero:

x = 1/2 · a · t²

At t = 9.9 s, x = 71 m

71 m = 1/2 · a · (9.9 s)²

2 · 71 m / (9.9 s)² = a

a = 1.4 m/s²

The acceleration of the sprinter is 1.4 m/s²

3 0

4 years ago

A jet airplane is in level flight. The mass of the airplane is m=8950 kg. The airplane travels at a constant speed around a circ

Mice21 [21]

Answer:

The net force is 91780.8 N.

Explanation:

mass, m = 8950 kg

Radius, R = 9.33 miles = 15015.2 m

Time, T = 0.123 h = 442.8 s

There are two forces acting on the plane.

Horizontal force is the centripetal force and the vertical force is the weight.

$Fx =m R w^2\\\\Fx = m R \frac{4\pi^2}{T^2}\\\\Fx = 8950\times 15015.2\times \frac{4\times 3.14\times 3.14}{442.8\times 442.8}\\\\Fx = 27030.8 N \\\\Fy = m g \\\\ Fy = 8950\times 9.8 \\\\Fy = 87710 N$

The net force is

$F = \sqrt{Fx^2 + Fy^2}\\\\F = \sqrt {27030.8^2 + 87710^2}\\\\F = 91780.8 N$

7 0

4 years ago

. A block of mass 4.0 kg on a spring has displacement as a function of time given by, x (t) = (1.0 cm) cos [(2.0 rad/s) t + 0.25

svlad2 [7]

Answer and Explanation:

1. Evaluate the function x(t) at t=0.5

$x(t)=1cos(2t+0.25)\\x(0.5)=cos(2*0.5+0.25)=cos(1+0.25)=cos(1.25)=0.3153223624\approx0.31cm$

2. The period of motion T can be calculated as:

$T=\frac{2\pi}{\omega}$

Where:

$\omega=2rad/s$

So:

$T=\frac{2\pi}{2}=\pi\approx3.14s$

3. The angular frequency can be expressed as:

$\omega=\sqrt{\frac{k}{m} }$

Solving for k:

$k=(\omega)^2*m=(2)^2*4=4*4=16\frac{N}{m}$

4. Find the derivate of x(t):

$\frac{dx}{dt} =v(t)=-2sin(2t+0.25)$

Now, the sine function reach its maximum value at π/2 so:

$2t+025=\frac{\pi}{2}$

Solving for t:

$t=\frac{\frac{\pi}{2} -0.25}{2} =0.6603981634s$

Evaluating v(t) for 0.6603981634:

$v(0.6603981634)=-2sin(2*0.6603981634+0.25)=-2sin(\frac{\pi}{2} )=-2*1=2$

So the maximum speed of the block is:

$v(0.6603981634)=2cm/s=0.02m/s$

In the negative direction of x-axis

5. The force is given by:

$F=kx$

The cosine function reach its maximum value at 2π so:

$2t+0.25=2\pi$

Solving for t:

$t=\frac{2\pi-0.25}{2} =3.016592654s$

Evaluating x(t) for 3.016592654:

$x(3.016592654)=cos(2*3.016592654+0.25)=cos(2\pi)=1cm=0.01m$

Therefore the the maximum force on the block is:

$F=16*0.01=0.16N$

6 0

3 years ago

What mathematical formula correctly expresses the relationship between force, mass and acceleration? A. m = F + a B. F = m / a C

IRINA_888 [86]

D. F=ma

F is for force, and that equals two things, M for mass and A for acceleration. When mass is accelerated, it gives you force. Force equals multiplying mass and its acceleration.

3 0

3 years ago