Why is it important to define a frame of reference?a. An observer cannot be moving.
b. Motion must be defined relative to something.
c. It's impossible to measure motion.
d. A stationary observer is always moving.
Answers
Motion must be defined relative to something.
Here's an obvious, everyday example:
-- You're in a passenger jet, going to visit grandma on the
coast for the holidays.
-- You're sitting still in your seat, listening to some 'mp3's,
reading a book, and dozing off.
-- At the same time, people on the ground see you flying over
at almost 500 miles per hour.
Are you moving at 500 mph, or are you not moving at all ?
The answer is 'Yes. Both.'. It just depends on who's measuring your speed.
There's no such thing as your "real" speed. Motion is always
relative to something. Different reference = different speed.
It is important to define a frame of reference because motion must be defined relative to something. Hence option(b) is correct.
Further Explanation:
Frame of reference is a framework that is used for observation of physical phenomena. It consists of an observer, a coordinate system and positions with respect to the coordinate system.
(a)
Let us take an example of a trolley moving with velocity and a man on the ground at rest.
Since, the man's velocity is zero, the relative velocity of trolley with respect to the man is .
Now, if a man starts to run with speed and speed of trolley increases to two times of initial velocity
i.e.
, the relative velocity of trolley with respect to man is
.
Here, in both the conditions, the relative velocity of trolley with respect to time is same.
Therefore, it is wrong to say that an observer cannot be moving. Hence, option(a) is incorrect.
(b)
Let us take an example of a man on the ground at rest and a trolley moving with the velocity having an object placed in it. The object will also moves with the velocity
.
For a man, trolley is moving with velocity but for an object trolley is at rest because there is no relative motion between object and trolley.
Therefore, it is right to say that motion must be defined relative to something. Hence, option(b) is correct.
(c)
Let us take an example of a first object moving with velocity and a second object moving with velocity
in the opposite direction and a third object is at rest.
The relative velocity of first object with respect to second object is and the relative velocity of first object with respect to third object is
.
Here, the relative velocity of an object is different with respect to different object but all the motions are measurable.
Therefore, it is wrong to say that it's impossible to measure motion. Hence, option(c) is incorrect.
(d)
Let us take an example of two trains moving with same velocity in same direction.
Consider a man sitting in one train observes a man running in other train, then the man sitting is said to be stationary observer for the man running. Here, the man is stationary observer while in motion.
Now, if a man standing on the ground at rest will see the man on train, he will be called stationary observer. Here, the man is stationary observer while not in motion.
Therefore, it is wrong to say that a stationary observer is always moving. Hence, option(d) is incorrect.
Learn more:
1. Motion on a rough surface: brainly.com/question/7031524
2. Motion under the gravitational force: brainly.com/question/10934170
3. Principle of conservation of momentum: brainly.com/question/9484203
Answer Details:
Grade: High School
Subject: Physics
Chapter: Kinematics
Keywords:
Frame, reference, important, observer, motion, relative, velocity, speed, moving, measure, stationary, example, trolley, man and train.
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B. The force applied would be less, but the distance would be greater.
C. The force applied would be the same, but the distance would be shorter.
D. The force applied would be the same, but the distance would be greater.
Answers
If the person inserted a nail with a hammer instead of the screw with the screwdriver, the force applied would be greater, but the distance would be shorter. The correct option is A.
What is force?
The action of push or pull in order to make a body change its state of motion or rest is called Force.
As the force is pressure per unit area. Force is inversely proportional to the area over which force is to applied.
The hammer would take more force to insert the nail. The screw has its helix which is to be inserted and application of force is small.
Thus, the force applied would be greater, but the distance would be shorter. The correct option is A.
Learn more about force.
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t if the person inserted a nail with a hammer instead of the screw with the screwdriver?
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(m*v-m*u)/t = F
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soo, t = 1 sec
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Given :
Vector A has a magnitude of 63 units and points west, while vector B has the same magnitude and points due south.
To Find :
The magnitude and direction of
a) A + B .
b) A - B.
Solution :
Let , direction in north is given by +j and east is given by +i .
So , and
Now , A + B is given by :
Direction of A+B is 45° north of west .
Also , for A-B :
Direction of A-B is 45° south of west .
( When two vector of same magnitude which are perpendicular to each other are added or subtracted the resultant is always 45° from each of them)
Hence , this is the required solution .
Answers
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its body is too hot inside.
Moving around (using muscles) makes heat inside, and the animal needs
a way to get rid of the heat. Fast.
Evaporation is a very effective way to get rid of heat.
Human animals do it by perspiring. We excrete moisture through our skin,
and when the moisture evaporates, that takes heat away very efficiently.
That's why we like to fan ourselves when we're hot ... moving more air
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Dogs don't perspire, so they badly need another way to get rid of heat
in a hurry.
They do it through their mouth. They put water in their mouth if it's available,
or else just collect a lot of saliva in there if there's no other water, and then
they blow air over it to evaporate it and get rid of heat. Panting moves more
air over the moisture, which causes more evaporation and more heat loss.