A bus slows down uniformly from 75.0 km/h to 0 km/h in 21 s. How far does it travel before stopping?
Answers
As per the question,the bus slows down uniformly from 75 km/h to 0 km/h.
Hence the initial velocity of the bus[ u]=75 km/hr.
the final velocity of the bus [v]=0 km/h
the taken by the bus to stop [t]=21 s
we know that 1 km= 1000 m and 1 hour =3600 second.
Hence
=20.83 m/s
we are asked to calculate the stopping distance.
From equation of kinematics we know that-
v= u +at where a is the acceleration of the particle.
we have v= 0 km/h = 0 m/s and u= 75 km/h =20.83 m/s
t = 21 s
Putting these values in above equation we get-
0 = 20.83 +a×21
⇒ a×21 = -20.83 m/s
⇒a= -[20.83]÷21
[ Here negative sign indicates that particle is decelerating ]
Again from the equation of kinematics we know that-
Here s is the distance traveled. Putting the above quantities we get-
s = 218.7 metre. [ans]
Hence the bus will stop after a distance of 218.7 m.
1 hour = 3,600 seconds
1 km = 1,000 meters
75 km/hour = (75,000/3,600) m/s = 20-5/6 m/s
The average speed of the bus while it slows down is
(1/2)(20-5/6 + 0) = 10-5/12 m/s .
Traveling at an average of 10-5/12 m/s for 21 seconds,
the bus covers
(10-5/12) x (21) = 218.75 meters .
Related Questions
What kind of glass is used for car head lamp
The National Grid supplied a house with 18,000,000 J of energy in 1 hour. What was the average current supplied to the house during that hour?
If Mike does 25.5 J of work lifting a book 1.5 m onto a shelf what is the mass of the book in kilograms
A student who weighs 550 N is wearing a backpack that weighs 80 N. The student is standing still on level ground. Give your answers to the following questions in newtons. Remember, enter only the number; don't try to enter the units.a) What is the magnitude of the net force on the student?b) What is the magnitude of the contact force on the student by the backpack?c) What is the magnitude of the contact force on the student by the ground?
How high up must the 7th floor be?
If you had thrown it at the same speed but at the 28th floor, how far from the base of the building would it land?
Answers
1) 31.1 m/s
The rock has been thrown straight out of the window: its motion on the horizontal direction is simply a uniform motion, with constant speed , because no forces act in the horizontal direction. The speed in a uniform motion is given by
where S is the distance traveled and t the time taken.
In this case, the distance by the rock before hitting the ground is and the time taken is
, so the initial speed is given by
2) 67.1 m
In this part of the problem we are only interested in the vertical motion of the rock. The vertical motion is a uniformly accelerated motion, with constant acceleration (acceleration of gravity) towards the ground. In a uniformly accelerated motion, the distance traveled by the object is given by
where t is the time. Substituting a=9.8 m/s^2 and t=3.7 s, we can find S, the vertical distance covered by the rock, which corresponds to the height of the 7th floor:
3) 230.1 m
The height of the 7th floor is 67.1 m. So we can assume that the height of each floor is
And so, the height of the 28th floor is
We can find the total time of the fall in this case by using the same formula of the previous part:
In this case, S=268.8 m, so we can re-arrange the formula to find t
And now we can consider the motion of the rock on the horizontal direction: we know that the rock travels at a constant speed of v=31.1 m/s, so the distance traveled is
And this is how far from the building the rock lands.
115/3.7 =31.08m/s^2
Answers
Answer:
You Got me im Imposter
Explanation:
Answers
Matter can be defined as something that has mass and occupies space. They are present in the atmosphere in different phases. Thus, the correct option is C.
What is Matter?
Matter is any substance which is made up of various types of particles that occupies some physical space and has mass. According to the modern physics, there are various types of particles with each having a specific mass and size. The most common examples of these material particles are electrons, protons and neutrons.
Matter is present in different phases in the atmosphere. The three phases are solids, liquids, and gases. All of these phases show mass and occupies some space.
Therefore, the correct option is C.
Learn more about Matter here:
#SPJ5
Answer: C
Explanation:
Matter is anything that has mass and takes up space. People, paper, goats, chairs and even water is Matter!
magnet
B. The north pole of one magnet is far away from the north pole of
the other magnet.
C. The north pole of one magnet is far away from the south pole of
the other magnet.
D. The south pole of one magnet is near the south pole of the other
magnet
Answers
B. only a S pole
C. both a N and S pole
D.neither a N nor a S pole
Answers
Answer:
I guess it was C.both a N and S pole...
Comment if I was wrong.
Answers
v = 8m/s
λ = 2
f = v \div λ
f = 8 \div 2
f = 4hz