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Stella [2.4K]
3 years ago
6

Two boys on skateboards are facing each other. They push off, the first boy (mass: 43.8 kg) traveling backward at 2.1 m/s. If th

e second boy is now traveling at 3.09 m/s, what is his mass?
Physics
1 answer:
slega [8]3 years ago
5 0

Answer:

The mass of the second boy is, m = 29.77 kg

Explanation:

Given data,

The mass of first boy, M = 43.8 kg

The velocity of first boy, V = -2.1 m/s

The velocity of second boy, v = 3.09 m/s

Then mass of second boy, m = ?

According to the law of conservation of momentum,

                                    mv + MV = 0

                                     m = - MV / v

Substituting the values,

                                     m = 43.8 x 2.1 / 3.09

                                      m = 29.77 kg

Hence, the mass of the second boy is, m = 29.77 kg

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When Woods hits a 0.04593 kg golf ball, the golf ball is usually traveling around 281 kilometers per hour. What average force do
Semenov [28]

Answer:

128.9 N

Explanation:

The force exerted on the golf ball is equal to the rate of change of momentum of the ball, so we can write:

F=\frac{\Delta p}{\Delta t}

where

F is the force

\Delta p is the change in momentum

\Delta t=0.030 s is the time interval

The change in momentum can be written as

\Delta p = m(v-u)

where

m = 0.04593 kg is the mass of the ball

u = 0 is the initial velocity of the ball

v=281 km/h =78.1 m/s is the final velocity of the ball

Substituting into the original equation, we find the force exerted on the golf ball:

F=\frac{m(v-u)}{\Delta t}=\frac{(0.04593)(78.1-0)}{0.030}=128.9 N

7 0
3 years ago
The temperature of a black body is 500 and its radiation is of wavelength 600 . If the number of oscillators with energy is 100
stiks02 [169]

Answer: An equation is missing in your question below is the missing equation

a) ≈ 8396

b) 150 nm/k

Explanation:

<u>A) Determine the number of Oscillators in the black body</u>

number of oscillators = 8395

attached below is the detailed solution

<u>b) determine the peak wavelength of the black body </u>

Black body temperature = 20,000 K

applying Wien's law / formula

λmax = b / T  ------ ( 1 )

T = 20,000 K

b = 3 * 10^6 nm

∴  λmax = 150 nm/k

4 0
2 years ago
One billiard ball is shot east at 2.00 m/s. A second, identical billiard ball is shot west at 1.00 m/s. The balls have a glancin
dimulka [17.4K]

Answer:

Velocity is 1.73 m/s along 54.65° south of east.

Explanation:

Let unknown velocity be v, mass of billiard ball be m and east direction be positive x axis.

Here momentum is conserved.

Initial momentum = Final momentum

Initial momentum = m x 2i + m x (-1)i = m i

Final momentum = m x v + m x 1.41 j = mv + 1.41 m j

Comparing

mi = mv + 1.41 m j

v = i - 1.41 j

Magnitude of velocity

      v=\sqrt{1^2+(-1.41)^2}=1.73m/s        

Direction,  

       \theta =tan^{-1}\left ( \frac{-1.41}{1}\right )=-54.65^0             

Velocity is 1.73 m/s along 54.65° south of east.

5 0
3 years ago
A ball is thrown vertically upwards from the edge of the cliff and hits the ground at the base of the cliff with a speed of 30 m
olya-2409 [2.1K]

To solve this problem we will apply the linear motion kinematic equations. From the definition of the final velocity, as the sum between the initial velocity and the product between the acceleration (gravity) by time, we will find the final velocity. From the second law of kinematics, we will find the vertical position traveled.

v = v_0 -gt

Here,

v = Final velocity

v_0 = Initial velocity

g = Acceleration due to gravity

t = Time

At t = 4s, v = -30m/s (Downward)

Therefore the initial velocity will be

-30 = v_0 -9.8(4)

v_0 = 9.2m/s

Now the position can be calculated as,

y = h +v_0t -\frac{1}{2}gt^2

When it has the ground, y=0 and the time is t=4s,

0 = h+(9.2)(4)-\frac{1}{2} (9.8)(4)^2

h = 41.6m

Therefore the cliff was initially to 41.6m from the ground

7 0
3 years ago
An object is hanging by a string from the ceiling of an elevator. The elevator is moving upward with a constant speed. What is t
xeze [42]

Answer:

The magnitude of the tension in he string is equal to the magnitude of the weight of the object.

Explanation:

According to the Newton's 1st law, An object will remain at rest or in uniform motion in a straight line unless acted upon by an unbalanced force.

In here, the elevator is moving with a constant speed. So the object must have the equal constant speed. Which means, it has a uniform motion. According to Newton's 1st law, the total unbalanced force on the object must be zero . As we know, there are only two forces are on the object and they are,

The tension in string(T)   ,   The weight of the object(W) .

                                  ∴ F    =   0

                                 T  -  W  =   0

So to balanced those forces, the magnitude of the tension in the string must be equal to the magnitude of the weight of  the object.  

       

8 0
2 years ago
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