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3 years ago

What is the tangential velocity of a record player which makes 11 revolutions in 20 seconds?

Physics

1 answer:

slava [35]3 years ago

7 0

Answer:

The tangential velocity of a rotating object is:

v = r*w

where r is the radius, and w is the angular velocity.

w = 2*pi*f

where f is the frequency.

We know that the record plater does 11 revolutions in 20 seconds, then it does:

11 rev/20s = 0.55 rev/s = f

then we have:

w = 2*pi*0.55 s^-1 = 2*3.14*0.55 s^-1 = 3.454 s^-1

The radius of a record player is really variable, it is around 10 inches, so i will use r = 10in, which is the rotating part of the record player.

then the tangential velocity is:

v = 10in*3.454 s^-1 = 34.54 in/s

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A 1232 kg car moving north at 25.6 m/s collides with a 2028 kg car moving north at 17.5 m/s . They stick together. In what direc

Citrus2011 [14]

Answer:

I. Angle = 41.7° Northeast.

II. Vr = 7.08m/s

Explanation:

Let the two cars be denoted by A and B

Given the following data;

Mass of car A = 1232 Kg

Velocity of car A = 25.6 m/s

Mass of car B = 2028 Kg

Velocity of car B = 17.5m/s

First of all, we would solve for momentum;

Momentum = mass × velocity

Momentum, M1 = 1232 × 25.6

Momentum, M1 = 31539.2 Kgm/s

Momentum, M2 = 2028 × 17.5

Momentum, M2 = 35490 Kgm/s

Now, let's find the resultant momentum using the Pythagoras theorem;

R² = M1² + M2²

R² = 31539.2² + 35490²

R² = 994721136.6 + 1259540100

R² = 2254261237

Taking the square root of both sides, we have

Resultant momentum, R = 47479.06 Kgm/s

To find the direction;

Angle = tan¯¹(M1/M2)

Angle = tan¯¹(31539.2/35490)

Angle = tan¯¹(0.89)

Angle = 41.7° Northeast.

To find the speed;

R = (M1 + M2)Vr

47479.06 = (31539.2 + 35490)Vr

47479.06 = 67029.2Vr

Vr = 47479.06/67029.2

Vr = 7.08m/s

6 0

2 years ago

A spring with spring constant 15 N/m hangs from the ceiling. A ball is attached to the spring and allowed to come to rest. It is

Tpy6a [65]

Answer:

1)m=89.01 g

2)V(max) = 97.3 cm/s

Explanation:

Given that

K= 15 N/m

The maximum amplitude ,A=7.5 cm = 0.075 m

Given that 31 oscillations in 15 seconds ,this means that frequency f

f=\dfrac{31}{15}

f=2.066 Hz

lets take mass of the ball = m kg

$f=\dfrac{1}{2\pi}\times \sqrt{\dfrac{K}{m}}$

$m=\dfrac{1}{4\times \pi^2}\times{\dfrac{K}{f^2}}$

$m=\dfrac{1}{4\times \pi^2}\times{\dfrac{15}{2.066^2}}$

m=0.08901 kg

m=89.01 g

The maximum speed

V(max)= ω x A

ω = 2π f= 2 x π x 2.066 = 12.98 rad/s

V(max) = 12.98 x 0.075 =0.973 m/s

V(max) = 97.3 cm/s

3 0

3 years ago

43- The lighter you are, the stronger the air resistance because:

expeople1 [14]

Answer:

b) The gravitational pull will be weak.

Explanation:

Less mass requires less force. Gravity or gravitational pull is a force. In order for you to stay in place and not go through the ground, however, you require something to pulling you away from the Earth. That's why we have air resistance.

5 0

3 years ago

The horizontal surface on which the block slides is frictionless.The speed of the block before it touches the spring is 6.0 m/s.

Aloiza [94]

Answer:

V = 5.4 m/s

Explanation:

It is given that,

Let mass of the block, m = 10 kg

Spring constant of the spring, k = 2 kN/m = 2000 N/m

Speed of the block, v = 6 m/s

Compression in the spring, x = 15 cm = 0.15 m

Let V is the speed of the block moving at the instant the spring has been compressed 15 cm. It can be calculated using the conservation of energy of spring mass system.

$\dfrac{1}{2}m^2=\dfrac{1}{2}kx^2+\dfrac{1}{2}mV^2$