Why a plastic pen which is rubbed with hair,is able to attract small pieces of papers

A 125-kg astronaut (including space suit) acquires a speed of 2.50 m/s by pushing off with her legs from a 1900-kg space capsule

ryzh [129]

(a) 0.165 m/s

The total initial momentum of the astronaut+capsule system is zero (assuming they are both at rest, if we use the reference frame of the capsule):

$p_i = 0$

The final total momentum is instead:

$p_f = m_a v_a + m_c v_c$

where

$m_a = 125 kg$ is the mass of the astronaut

$v_a = 2.50 m/s$ is the velocity of the astronaut

$m_c = 1900 kg$ is the mass of the capsule

$v_c$ is the velocity of the capsule

Since the total momentum must be conserved, we have

$p_i = p_f = 0$

so

$m_a v_a + m_c v_c=0$

Solving the equation for $v_c$ , we find

$v_c = - \frac{m_a v_a}{m_c}=-\frac{(125 kg)(2.50 m/s)}{1900 kg}=-0.165 m/s$

(negative direction means opposite to the astronaut)

So, the change in speed of the capsule is 0.165 m/s.

(b) 520.8 N

We can calculate the average force exerted by the capsule on the man by using the impulse theorem, which states that the product between the average force and the time of the collision is equal to the change in momentum of the astronaut:

$F \Delta t = \Delta p$

The change in momentum of the astronaut is

$\Delta p= m\Delta v = (125 kg)(2.50 m/s)=312.5 kg m/s$

And the duration of the push is

$\Delta t = 0.600 s$

So re-arranging the equation we find the average force exerted by the capsule on the astronaut:

$F=\frac{\Delta p}{\Delta t}=\frac{312.5 kg m/s}{0.600 s}=520.8 N$

And according to Newton's third law, the astronaut exerts an equal and opposite force on the capsule.

(c) 25.9 J, 390.6 J

The kinetic energy of an object is given by:

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

where

m is the mass

v is the speed

For the astronaut, m = 125 kg and v = 2.50 m/s, so its kinetic energy is

$K=\frac{1}{2}(125 kg)(2.50 m/s)^2=390.6 J$

For the capsule, m = 1900 kg and v = 0.165 m/s, so its kinetic energy is

$K=\frac{1}{2}(1900 kg)(0.165 m/s)^2=25.9 J$

3 0

3 years ago

An internal explosion breaks an object, initially at rest, into two pieces: A and B. Piece A has 1.9 times the mass of piece B.

Helen [10]

Kinetic energy of pieces A and B are 2724 Joule and 5176 Joule respectively.

<h3>What is the relation between the masses of A and B?</h3>

Let mass of piece A = Ma

Mass of piece B = Mb

Velocities of pieces A and B are Va and Vb respectively.
As per conservation of momentum,

Ma×Va = Mb×Vb

Here, Ma=1.9Mb

So, 1.9Mb × Va = Mb×Vb

=> 1.9Va = Vb

<h3>What are the kinetic energy of piece A and B?</h3>

Expression of kinetic energy of piece A = 1/2 × Ma × Va²
Kinetic energy of piece B = 1/2 × Mb × Vb²
Total kinetic energy= 7900J

=>1/2 × Ma × Va² + 1/2 × Mb × Vb² = 7900

=> 1/2 × Ma × Va² + 1/2 × (Ma/1.9) × (1.9Va)² = 7900

=> 1/2 × Ma × Va² ×(1+1.9) = 7900 j

=> 1/2 × Ma × Va² = 7900/2.9 = 2724 Joule

Kinetic energy of piece B = 7900 - 2724 = 5176 Joule

Thus, we can conclude that the kinetic energy of piece A and B are 2724 Joule and 5176 Joule respectively.

Learn more about the kinetic energy here:

brainly.com/question/25959744

#SPJ1

5 0

1 year ago

It is correct to say that impulse is equal toA) momentum.B) the change in momentum.C) the force multiplied by the distance the f

Elena-2011 [213]

Answer:

B) the change in momentum.

Explanation:

The impulse is defined as the product between the force applied on an object (F) and the duration of the collision ( $\Delta t$ ):

$J=F \Delta t$ (1)

We can rewrite the force by using Newton's second law, as the product between mass (m) and acceleration (a):

$F=ma$

So, (1) becomes

$J=ma \Delta t$

Now we can also rewrite the acceleration as ratio between the change in velocity and change in time: $a=\frac{\Delta v}{\Delta t}$ . If we substitute into the previous equation, we find

$J=m\frac{\Delta v}{\Delta t}\Delta t=m\Delta v$

And the quantity $m\Delta v$ is equivalent to the change in momentum, $\Delta p$ .

6 0

3 years ago

What wavelength would a ripple in water have if the frequency is 1.8 Hz and a

Yuki888 [10]

Explanation:

825m/s / 1.8Hz = 458.33m

6 0

2 years ago

Read 2 more answers

How do resistors in parallel affect the total resistance?

4vir4ik [10]

Answer:

They're going to increase the total resistance as $R_{T} = \sum\limits_{i=1}^N \left(\frac{1}{R_i} \right)^{-1}$

Explanation:

If the resistors are in parallel, the potential difference is the same for each resistor. But the total current is the sum of the currents that pass through each of the resistors. Then

$I = I_1 + I_2 + ... + I_N$

where

$I_i = \frac{V_i}{R_i}$

but

$V_i = V_j = V$ for $i,j= 1, 2,..., N$

so

$I = \frac{V}{R_1}+ \frac{V}{R_2} + ... + \frac{V}{R_N} = \left(\frac{1}{R_1} +\frac{1}{R_2} + ... + \frac{1}{R_N}\right)V = \frac{V}{R_T}$

where

$R_T = \left(\frac{1}{R_1} +\frac{1}{R_2} + ... + \frac{1}{R_N}\right)^{-1} =\sum\limits_{i=1}^N \left(\frac{1}{R_i} \right)^{-1}$

4 0

3 years ago

Why a plastic pen which is rubbed with hair,is able to attract small pieces of papers​

Why a plastic pen which is rubbed with hair,is able to attract small pieces of papers