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3 years ago

PLEASE HELP!! DUE IN 40 MINUTES!!

1 answer:

6 0

A frame of reference can be thought of as the state of motion of the observer of some event. For example, if you're sitting on a lawn chair watching a train travel past you ... you could even watch a glass of water sitting on a table inside the train move ... This seems like a simple and obvious example, yet when you take a step

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A 77.0−kg short-track ice skater is racing at a speed of 12.6 m/s when he falls down and slides across the ice into a padded wal

sukhopar [10]

Answer:

-6112.26 J

Explanation:

The initial kinetic energy, $KE_i$ is given by

$KE_i=0.5mv_1^{2$ } where m is the mass of a body and $v_i$ is the initial velocity

The final kinetic energy, $KE_f$ is given by

$KE_f=0.5mv_f^{2}$ where $v_f$ is the final velocity

Change in kinetic energy, $\triangle KE$ is given by

$\triangle KE=KE_f-KE_i=0.5mv_f^{2}-0.5mv_1^{2}=0.5m(v_f^{2}-v_i^{2})$

Since the skater finally comes to rest, the final velocity is zero. Substituting 0 for $v_f$ and 12.6 m/s for $v_i$ and 77 Kg for m we obtain

$\triangle KE=0.5*77*0^{2}-0.5*77*(0^{2}-12.6^{2})=-6112.26 J$

From work energy theorem, work done by a force is equal to the change in kinetic energy hence for this case work done equals <u>-6112.26 J</u>

3 0

3 years ago

A 50 kg astronaut floating in space throws her 2 kg wrench to the left at 10

Hoochie [10]

The astronaut will move at 0.4 m/s in the opposite direction to the wrench

Explanation:

We can solve this problem by using the law of conservation of momentum. In fact, the total momentum of the astronaut-wrench system must be conserved before and after the launch.

Before the launch, the total momentum is zero, since the astronaut is at rest:

p = 0 (1)

After the launch, the total momentum is:

$p=mv+MV$ (2)

where :

m = 2 kg is the mass of the wrench

v = 10 m/s is the velocity of the wrench

M = 50 kg is the mass of the astronaut

V is the recoil velocity of the astronaut

Since momentum is conserved, we can write (1) = (2), and so we can solve for V:

$0=mv+MV\\V=-\frac{mv}{M}=-\frac{(2)(10)}{50}=-0.4 m/s$

And the negative sign means that the astronaut will move in the opposite direction to the wrench.

Learn more about conservation of momentum:

brainly.com/question/7973509

brainly.com/question/6573742

brainly.com/question/2370982

brainly.com/question/9484203

#LearnwithBrainly

8 0

3 years ago

A wave traveling in water has a frequency of 250 Hz and a wavelength of 6.0m. What is the speed of the wave?

vladimir2022 [97]

Since you are looking for the speed, you need to rearrange the formula which is f = speed / wavelength. That should give you speed = f (wavelength.) All you need to do next is to substitute the value to the following equation. speed = 250 Hz (6.0m) that should leave you with 1500 m/s which is very fast.

6 0

4 years ago

The two forces in each pair can either both act on the same body or they can act on different bodies. The two forces in each pai

kotykmax [81]

Answer: The given statement is false.

Explanation:

According to Newton's third law of motion, every action has an equal and opposite reaction. So, when we apply force in one direction on an object then the object also applies a force in the opposite direction.

Hence, it is true that two forces in each pair of forces act in opposite directions.

For example, when we push a wooden box of 20 kg in the forward direction then the box will also apply a force in the opposite direction.

But the statement two forces in each pair can either both act on the same body or they can act on different bodies is false.

5 0

3 years ago

Braddy connected the loose wire to the battery and created an electromagnet. He picked up 45 thumb tacks with his electromagnet,

Katarina [22]

Answer:

C) Use two batteries instead of one.

Explanation:

-Strength of an electromagnet depends on the electrical current which flows through the wires.

-Two batteries have a higher current than one and thus higher strength in the electromagnet.

3 0

3 years ago