PHYSICS HIGH SCHOOL

A bus slams on its breaks and goes from 30 km/hr to 15km/hr in 4 seconds. What is its acceleration?

Answers

Answer 1
Answer:
Acceleration = (change in speed) / (time for the change).

Change in speed = (15 - 30) = -15 km/hr
Time for the change = 4 sec

Acceleration = (-15 km/hr) / (4 sec) = -3.75 km/hr per second .

Is that a lot ?  Not much ?

Let's convert it to a unit that we can think about:

     (-15 km/hr) x (1,000 m/km) x (1 hr / 3,600 sec) =

           (-15 x 1,000) / (3,600)  =  -(4 and 1/6) m/sec .

So the acceleration of the bus is    -(4 and 1/6) m/sec² .

The negative sign means that it slowed down.

(4 and 1/6) m/sec²  is about  42%  of the acceleration of gravity ...
the acceleration the bus would have if it drove off of a cliff.

When the car or the bus you're riding in slows down at that rate,
you feel  42%  of your weight pulling you forward against your
seat belt.  That's quite a drastic acceleration !

Related Questions

An unusual fog that is denser than air begins to fill a room. Should the people in the room walk out or crwl out? The people should.
What instrument converts electrical energy to sound or image signals in a radio or television?
Suppose nuclear physicists discovered a fission process that always produced two smaller nuclei and only one neutron. Would this eliminate the danger of meltdown in a nuclear power plant? Why or Why not- ? Explain.(Thanks to anyone who helps :)
Which term best describes the important pieces of information that scientists gather and record during an experiment?
What kind of energy do most electric inventions give off?

The initiative vs. guilt stage is an essential phase in a child’s development, where they learn to explore and take _______ while developing their sense of autonomy and control over their lives.

Answers

The initiative vs. guilt stage is an essential phase in a child’s development, where they learn to explore and take initiative while developing their sense of autonomy and control over their lives.

The answer is initiative.

Which statements explain current theories about dark energy and dark matter? Check all that apply.(correct) Space that appears empty actually contains dark energy and dark matter.
(correct) Dark matter does not emit electromagnetic radiation.
Scientists believe dark energy will cause the universe to collapse inward to a single point.
(correct) Scientists theorize that dark energy is causing the expansion of the universe to accelerate.
Dark matter includes all of the dust, ice, and debris that scientists observe in black holes.

just trynna help out future students

Answers

Answer:

Space that appears empty actually contains dark energy and dark matter

Dark matter does not emit electromagnetic radiation

Scientists theorize that dark energy is causing the expansion of the universe to accelerate

Explanation:

According to the current theories about dark energy and dark matter, scientists theorize that dark energy is causing the expansion of the universe to accelerate as dark matter does not emit electromagnetic radiation. Moreover, the space that appears empty actually contains dark energy and dark matter.

Answer:

A, B, D or 1, 2, 4

Explanation:

i did it on edge hope it helps

Which best describes how heat flows? A. Heat flows from a warmer object to a colder object. B. Heat flows in any direction. C. Heat flows from a colder object to a warmer object. D. All objects transfer to their heat to all other objects.

Answers

The statement which best describes how heat flows is that the heat generally flows from a warmer object to a colder object. Therefore, the correct option is A.

The mechanism of heat flow significantly describes the transfer of heat energy or enthalpy from one object to another. It is transferred through the process of conduction, convection, and radiation.

The object that is warmer in appearance may accumulate heat in enough amounts. This leads to an increase in its temperature and energy, While the mechanism of heat transfer generally initiates this warmer object to a colder object by conduction.

To learn more about Heat flow, refer to the link:

brainly.com/question/16055406

#SPJ2
Heat flows from a warmer object to a colder object

A 0.4-kg toy train car moving forward at 3 m/s collides with and sticks to a 0.8–kg toy car that is traveling in the opposite direction at –2 m/s. What is the size and direction of the final velocity of the two cars

Answers

Hey there!

Seems like you're looking for the size and direction to the final velocity of the two cars. To find it, you must solve it like this.

0.4 kg(3 m/s) + 0.8kg(–2 m/s) = 1.2 kg m/s -1.6 kg m/s = –0.4 kg m/s

–0.4 kg m/s = 1.2 kg(v) = (–0.4 kg m/s)/(1.2 kg) = v = –0.33 m/s


So, the cars are traveling at -0.33 m/s in the direction of the second car.


Hope this helps


Tobey

PLZ EXPLAIN THE EQUATION AND I WILL GIVE BRAINLIST You are out and about in the country and your father sees a rock that he really wants in the yard. Now you must get the very heavy rock into the back of a truck. The truck bed is 3 feet off the ground. Your father pulls out a 5-foot plank and begins to set up a ramp. At the same time, you (who know about mechanical advantage!) have found a plank that is 8 feet long, and you show it to your father. Which plank will give you the most mechanical advantage? Calculate the MA for each plank

Answers

Answer:

The 8 foot long plank

Explanation: hope this helps :)

suggest an experiment to prove that the rate of evaporation of a liquid depends on its surface area vapour already present in surrounding air"

Answers

That's two different things it depends on:

-- surface area exposed to the air
AND
-- vapor already present in the surrounding air.

Here's what I have in mind for an experiment to show those two dependencies:

-- a closed box with a wall down the middle, separating it into two closed sections;

-- a little round hole in the east outer wall, another one in the west outer wall,
and another one in the wall between the sections;
So that if you wanted to, you could carefully stick a soda straw straight into one side,
through one section, through the wall, through the other section, and out the other wall.

-- a tiny fan that blows air through a tube into the hole in one outer wall.

Experiment A:

-- Pour 1 ounce of water into a narrow dish, with a small surface area.
-- Set the dish in the second section of the box ... the one the air passes through
just before it leaves the box.
-- Start the fan.
-- Count the amount of time it takes for the 1 ounce of water to completely evaporate.
=============================
-- Pour 1 ounce of water into a wide dish, with a large surface area.
-- Set the dish in the second section of the box ... the one the air passes through
just before it leaves the box.
-- Start the fan.
-- Count the amount of time it takes for the 1 ounce of water to completely evaporate.
=============================
Show that the 1 ounce of water evaporated faster
when it had more surface area.
============================================
============================================

Experiment B:

-- Again, pour 1 ounce of water into the wide dish with the large surface area.
-- Again, set the dish in the second half of the box ... the one the air passes
through just before it leaves the box.
-- This time, place another wide dish full of water in the first section of the box,
so that the air has to pass over it before it gets through the wall to the wide dish
in the second section.  Now, the air that's evaporating water from the dish in the
second section already has vapor in it before it does the job.
-- Start the fan.
-- Count the amount of time it takes for the 1 ounce of water to completely evaporate.
==========================================
Show that it took longer to evaporate when the air
blowing over it was already loaded with vapor.
==========================================
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