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3 years ago

15

When aluminum foil is formed into a loose ball, it can float on water. But when the ball of foil is pounded flat with a hammer,

the foil sinks. why?

1 answer:

docker41 [41]3 years ago

8 0

Air caught in the ball of foil makes the ball less dense than water

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A worker drives a 0.554 kg spike into a rail tie with a 2.30 kg sledgehammer. The hammer hits the spike with a speed of 62.7 m/s

Goryan [66]

Answer:

Increase in total energy will be equal to the increase in the internal energy i.e $1130.246$ Joules

Explanation:

Given

Weight of sledge hammer $= 2.30$ kilogram

Speed of sledge hammer $= 62.7$ meter per second

Kinetic energy is equal to half the product of mass and velocity square

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

Substituting the value of mass and velocity, we get -

$KE = 0.5 * 2.30 * 62.7^2\\KE = 4520.9835$

It is given that one fourth of the energy is converted into internal energy

One fourth of kinetic energy is equal to

$\frac{1}{4} * 4520.9835\\= 1130.246$

Increase in total energy will be equal to the increase in the internal energy i.e $1130.246$ Joules

8 0

3 years ago

Read 2 more answers

A 75 kg bungee jumper leaps from a bridge. When he is 30 meters above the water, and moving at a speed of 20 m/s, the bungee cor

jasenka [17]

Answer:

k = 52.2 N / m

Explanation:

For this exercise we are going to use the conservation of mechanical energy.

Starting point. When it is 30 m high

Em₀ = K + U = ½ m v² + m g h

Final point. Right when you hit the water

$Em_{f}$ = K_{e} = ½ k x²

in this case the distance the bungee is stretched is 30 m

x = h

as they indicate that there are no losses, energy is conserved

Em₀ = Em_{f}

½ m v² + m g h = ½ k h²

k = $\frac{m (v^{2} + 2 g h)}{h^{2} }$

let's calculate

k = $\frac{75 \ ( 20^{2} + 2 \ 9.8 \ 30)}{30^{2} }$

k = 52.2 N / m

3 0

3 years ago

What's the definition of sound?

Temka [501]

<span>vibrations that travel through the air or another medium and can be heard when they reach a person's or animal's ear.</span>

4 0

4 years ago

Read 2 more answers

Please help <br><br>formula to calculate equivalent resistance

azamat

Answer:

(Equation 10.3. 2): RS=R1+R2+R3+R4+R5=20Ω+20Ω+20Ω+20Ω+10Ω=90Ω

6 0

3 years ago

2. A 2000 kg car with speed 12.0 m/s hits a tree. The tree does not move or

krek1111 [17]

a) The work done by the tree is $-1.44\cdot 10^5 J$

b) The amount of force applied is 2880 N

Explanation:

a)

According to the work-energy theorem, the work done on the car is equal to the change in kinetic energy of the car. Therefore, we can write:

$W=K_f - K_i = \frac{1}{2}mv^2 - \frac{1}{2}mu^2$

where

W is the work done on the car

m is the mass of the car

u is its initial speed

v is its final speed

For the car in this problem, we have:

m = 2000 kg

u = 12.0 m/s

v = 0 (since the car comes to a stop, after the crash)

Therefore, the work done by the tree on the car is:

$W=0-\frac{1}{2}(2000)(12.0)^2=-1.44\cdot 10^5 J$

The work is negative because it is done in the direction opposite to the direction of motion of the car.

b)

The work done by the tree on the car can also be rewritten as

$W=Fd$

where

F is the force applied on the car

d is the displacement of the car during the collision

In this situation, we have:

$W=-1.44\cdot 10^5 J$ is the work done

$d=50.0 cm = 0.50 m$ is the displacement of the car during the collision

Solving the equation for F, we find the force exerted by the tree on the car:

$F=\frac{W}{d}=\frac{-1.44\cdot 10^5 J}{0.50}=-2880 N$

Where the negative sign means the force is applied opposite to the direction of motion of the car. Therefore, the magnitude of the force applied is 2880 N.

Learn more about work:

brainly.com/question/6763771

brainly.com/question/6443626

#LearnwithBrainly

3 0

4 years ago