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3 years ago

Please help me with these two multiple choice questions!

Physics

1 answer:

mafiozo [28]3 years ago

7 0

Answer:

11 is A and 12 is C

Explanation:

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In this dark-colored forest, you started with 50% light moths and 50% dark moths. At the end of your simulation, was there a hig

krek1111 [17]

Dark moths because they use their color to blend in with the trees to hide from birds

5 0

2 years ago

A 0.50 kilogram ball is held at a height of 20 meters. What is the kinetic energy of the ball when it reaches halfway after bein

Elis [28]

Answer:

A. 49 joules

Step By Step Solution:

Via kinematic equations we can must first determine the velocity of this object after 10 meters (since halfway of 20 meters is 10).

$v_{final}^2=v_{initial}^2+2gd$

Where the initial velocity is zero since it's held at a height of 20 meters, hence it's not moving initially, g is the average gravity on Earth 9.8 m/s^2 and d is the distance this object will travel so 10 meters. By plugging these values in we obtain:

$v_{final}^2=0+2(9.8)(10)\\\\v_{final}=\sqrt{2(9.8)(10)}=14m/s$

And the equation for kinetic energy is :

$K.E.=\frac{1}{2}mv^2=\frac{1}{2}(0.5kg)(14m/s)^2=49J$

So the kinetic energy halfway after being released is 49 joules.

3 0

3 years ago

A 5,000 kg freight car moving at 2 m/s runs into a 10,000 kg freight car at rest. They couple upon collision and move away as on

m_a_m_a [10]

Answer:

option D

Explanation:

given,

mass of the freight car (m) = 5,000 Kg

initial speed of car (u)= 2 m/s

mass of the freight car (M)= 10,000 Kg

initial speed (u')= 0 m/s

speed after collision (V)= ?

using conservation of momentum

m u + M u' = (M + m) V

5000 x 2 + 10000 x 0 = (5000 + 10000) V

$V = \dfrac{10000}{15000}$

$V = \dfrac{10}{15}$

$V = \dfrac{2}{3}$

couples move away with the speed of $V = \dfrac{2}{3}$

Hence, the correct answer is option D

4 0

4 years ago

Two protons are released from rest when they are 0.750 {\rm nm} apart.

Alex787 [66]

Explanation:

Given:

m = 1.673 × 10^-27 kg

Q = q = 1.602 × 10^-19 C

r = 0.75 nm

= 0.75 × 10^-9 m

Energy, U = (kQq)/r

Ut = 1/2 mv^2 + 1/2 mv^2

1.673 × 10^-27 × v^2 = (8.99 × 10^9 × (1.602 × 10^-19)^2)/0.75 × 10^-9

v = 1.356 × 10^4 m/s

F = (kQq)/r^2

F = m × a

1.673 × 10^-27 × a = ((8.99 × 10^9 × (1.602 × 10-19)^2)/(0.075 × 10^-9)^2

a = 2.45 × 10^17 m/s^2.

4 0

3 years ago

One way to create static electricity is to ____________.

Pie

Answer:

C. Rub two things together.

Explanation:

Rubbing two things together causes friction which forms energy and there you have it, static electricity. Take a fuzzy sweater and rub it against another fuzzy sweater and then touch it. The energy stored will release in the form of shock.

8 0

4 years ago