Một dây nhôm dài 10 m khi ở 25 độ C. Biết khi nhiệt độ tăng thêm 1 độ C thì chiều dài 1m dây nhôm sẽ tăng thêm 0,024mm.

A 1.00 kg solid, uniform disk rolls without slipping across a level surface, translating at 3.00 m/s. If the disk's radius is 0.

cluponka [151]

Explanation:

Given that,

Mass of the disk, m = 1 kg

Translational speed of the disk, v = 3 m/s

Radius of the disk, r = 0.39 m

(a) Let K is the tranlational kinetic energy of the disk. Its formula is given by :

$K=\dfrac{1}{2}mv^2$

$K=\dfrac{1}{2}\times 1\times 3^2$

K = 4.5 J

(b) Let K' is the rotational kinetic energy of the disk. Its formula is given by :

$K'=\dfrac{1}{2}I\omega^2$

$K'=\dfrac{1}{2}\dfrac{mr^2}{2}(\dfrac{v}{r})^2$

$K'=\dfrac{1}{4}mv^2$

$K'=\dfrac{1}{4}\times 1\times 3^2$

K' = 2.25 J

Hence, this is the required solution.

5 0

3 years ago

Which of the following statements are true?

inessss [21]

Answer:

a. If an object's speed is constant, then its acceleration must be zero.

FALSE

As we know that acceleration is defined as the rate of change in velocity

$a = \frac{d\vec v}{dt}$

so we can not say anything about the acceleration when speed is given to as and no information is given about velocity

b. If an object's acceleration is zero, then its speed must be constant.

TRUE

As we know that acceleration is defined as the rate of change in velocity

$a = \frac{d\vec v}{dt}$

Since we know that if acceleration is 0 then velocity must be constant and hence speed is also constant

c. If an object's velocity is constant, then its speed must be constant.

TRUE

Since velocity is constant then it shows that its magnitude and direction both are constant so its speed is also constant.

d. If an object's acceleration is zero, its velocity must be constant.

TRUE

As we know that acceleration is defined as the rate of change in velocity

$a = \frac{d\vec v}{dt}$

Since we know that if acceleration is 0 then velocity must be constant

e. If an object's speed is constant, then its velocity must be constant.

FALSE

Speed is just the magnitude so we can not say about its direction and hence if speed is constant then velocity may or may not change

7 0

3 years ago

A toboggan approaches a snowy hill moving at 11.7 m/s. The coefficients of static and kinetic friction between the snow and the

soldi70 [24.7K]

Answer:

The acceleration of the toboggan going up and down the hill is 8.85 m/s² and 3.74 m/s².

Explanation:

Given that,

Speed = 11.7 m/s

Coefficients of static friction = 0.48

Coefficients of kinetic friction = 0.34

Angle = 40.0°

(a). When the toboggan moves up hill, then

We need to calculate the acceleration

Using formula of acceleration

$a=g(\sin\theta+\mu_{k}\cos\theta)$

Put the value into the formula

$a=9.8(\sin40+0.34\times\cos40)$

$a=8.85\ m/s^2$

(b). When the toboggan moves up hill, then

We need to calculate the acceleration

Using formula of acceleration

$a=g(\sin\theta-\mu_{k}\cos\theta)$

Put the value into the formula

$a=9.8(\sin40-0.34\times\cos40)$

$a=3.74\ m/s^2$

Hence, The acceleration of the toboggan going up and down the hill is 8.85 m/s² and 3.74 m/s².

5 0

3 years ago

What are 3 wave properties?

Alex Ar [27]

Amplitude: the height of the wave
wavelenght: the distance betweeen adjacent crests
period: the time it takes for one complete wave to pass a given point

8 0

3 years ago

Read 2 more answers

What can you do to promote Americanism and love of our country?

snow_tiger [21]

There are a couple of things one can do to promote Americanism and love of one's country. One thing that can be done is the promotion of American history and the explanation of why, how, and what has America achieved thus far and why that is something that should be looked at with respect.

4 0

3 years ago