All categories

3 years ago

Kiran runs along a straight road of length 150 m. After

Physics

1 answer:

Alexandra [31]3 years ago

4 0

Answer:

Explanation:

Speed and velocity are not the same thing, as I'm sure you have determined while in physics. To find the average speed, we add the total distance run by Kiran and divide that total number of meters by the number of seconds it took to do this (just because I am going to state the speed and velocity in terms of m/s as opposed to m/min). To find the average velocity, we add the displacements together and divide by the total time. First the average speed:

$s=\frac{150+150}{60}=\frac{300}{60}=5\frac{m}{s}$

Velocity has direction. If Kiran runs to the end of the road (which we will call positive) and then runs back to the start (that direction will be negative), then his displacement fits into the velocity equation as

$v=\frac{150+(-150)}{60}=0$ That means, even though he ran a lot and I'm sure he was very tired, his average velocity for the trip was 0 m/s. When velocity is 0, remember that that means that the total displacement was 0.

You might be interested in

Bill throws a tennis ball to his dog. He throws the ball at a speed of 15 m/s at an angle of 30° to the horizontal. Assume he th

Sidana [21]

1a) Bill and the dog must have a speed of 13.0 m/s

1b) The speed of the dog must be 22.5 m/s

2a) The ball passes over the outfielder's head at 3.33 s

2b) The ball passes 1.2 m above the glove

2c) The player can jump after 2.10 s or 3.13 s after the ball has been hit

2d) One solution is when the player is jumping up, the other solution is when the player is falling down

Explanation:

1a)

The motion of the ball in this problem is a projectile motion, so it follows a parabolic path which consists of two independent motions:

- A uniform motion (constant velocity) along the horizontal direction

- An accelerated motion with constant acceleration (acceleration of gravity) in the vertical direction

In part a), we want to know at what speed Bill and the dog have to run in order to intercept the ball as it lands on the ground: this means that Bill and the dog must have the same velocity as the horizontal velocity of the ball.

The ball's initial speed is

u = 15 m/s

And the angle of projection is

$\theta=30^{\circ}$

So, the ball's horizontal velocity is

$v_x = u cos \theta = (15)(cos 30)=13.0 m/s$

And therefore, Bill and the dog must have this speed.

1b)

For this part, we have to consider the vertical motion of the ball first.

The vertical position of the ball at time t is given by

$y=u_yt+\frac{1}{2}at^2$

where

$u_y = u sin \theta = (15)(sin 30) = 7.5 m/s$ is the initial vertical velocity

$a=g=-9.8 m/s^2$ is the acceleration of gravity

The ball is at a position of y = 2 m above the ground when:

$2=7.5t + \frac{1}{2}(-9.8)t^2\\4.9t^2-7.5t+2=0$

Which has two solutions: t=0.34 s and t=1.19 s. We are told that the ball is falling to the ground, so we have to consider the second solution, t = 1.19 s.

The horizontal distance covered by the ball during this time is

$d=v_x t =(13.0)(1.19)=15.5 m$

The dog must be there 0.5 s before, so at a time

t' = t - 0.5 = 0.69 s

So, the speed of the dog must be

$v_x' = \frac{d}{t'}=\frac{15.5}{0.69}=22.5 m/s$

2a)

Here we just need to consider the horizontal motion of the ball.

The horizontal distance covered is

$d=98 m$

while the horizontal velocity of the ball is

$v_x = u cos \theta = (34)(cos 30)=29.4 m/s$

where u = 34 m/s is the initial speed.

So, the time taken for the ball to cover this distance is

$t=\frac{d}{v_x}=\frac{98}{29.4}=3.33 s$

2b)

Here we need to calculate the vertical position of the ball at t = 3.33 s.

The vertical position is given by

$y= h + u_y t + \frac{1}{2}at^2$

where

h = 1.2 m is the initial height

$u_y = u sin \theta = (34)(sin 30)=17.0 m/s$ is the initial vertical velocity

$a=g=-9.8 m/s^2$ is the acceleration of gravity

Substituting t = 3.33 s,

$y=1.2+(17)(3.33)+\frac{1}{2}(-9.8)(3.33)^2=3.5 m$

And sinc the glove is at a height of y' = 2.3 m, the difference in height is

y - y' = 3.5 - 2.3 = 1.2 m

2c)

In order to intercept the ball, he jumps upward at a vertical speed of

$u_y' = 7 m/s$

So its position of the glove at time t' is

$y'= h' + u_y' t' + \frac{1}{2}at'^2$

where h' = 2.3 m is the initial height of the glove, and t' is the time from the moment when he jumps. To catch the ball, the height must be

y' = y = 3.5 m (the height of the ball)

Substituting and solving for t', we find

$3.5 = 2.3 + 7t' -4.9t'^2\\4.9t'^2-7t'+12 = 0$

Which has two solutions: t' = 0.20 s, t' = 1.23 s. But this is the time t' that the player takes to reach the same height of the ball: so the corresponding time after the ball has been hit is

$t'' = t -t'$

So we have two solutions:

$t'' = 3.33 s - 0.20 s = 3.13 s\\t'' = 3.33 s - 1.23 s = 2.10 s$

So, the player can jump after 2.10 s or after 3.13 s.

2d)

The reason for the two solutions is the following: the motion of the player is a free fall motion, so initially he jump upwards, then because of gravity he is accelerated downward, and therefore eventually he reaches a maximum height and then he falls down.

Therefore, the two solutions corresponds to the two different part of the motion.

The first solution, t'' = 2.10 s, is the time at which the player catches the ball while he is in motion upward.

On the other hand, the second solution t'' = 3.13 s, is the time at which the player catches the ball while falling down.

Learn more about projectile motion:

brainly.com/question/8751410

#LearnwithBrainly

7 0

3 years ago

Jupiter and Saturn each have the same three basic cloud layers, but the spacing of the layers differs on the two planets. Why is

-Dominant- [34]

Answer:

b. Jupiter’s greater gravity has compressed the layers, so they are closer together there.

Explanation:

The value for Jupiter mass is 1.8981×10²⁷kg, while the mass of Saturn is 5.6832×10²⁶kg, so the different layers of clouds in Jupiter will be submitted to a greater gravitational pull because it has a bigger mass, as is established in the law of universal gravitation:

$F = G\frac{m1m2}{r^{2}}$ (1)

Where m1 and m2 are the masses of two objects, G is the gravitational constant and r is the distance between the two objects.

As it can be seen in equation 1, the gravitational force is directly proportional to the product of the masses of the objects, so if the mass increase the gravitational force will do it too.

For the case of Saturn, it has a lower mass so its layers of clouds will suffer a weaker gravitational pull. That leads to the three clouds being more spacing that the ones of Jupiter.

3 0

3 years ago

If zak's speed is 3.00 m/s when he starts to slide, what distance d will he slide before stopping? express your answer in meters

OverLord2011 [107]

That will depend on the coefficient of friction between the sliding surfaces, and also on Zak's weight. We don't have any of that information.

8 0

3 years ago

The part of the electromagnetic spectrum you can see is called ultraviolet light. Please select the best answer from the choices

Artyom0805 [142]

True because when the light bounces off a surface it creates a rainbow which we call roygbiv

4 0

4 years ago

A professor of physics gets a $200 a month raise. She figures that with her new monthly salary she can buy fewer number of goods

artcher [175]

Answer:

Her real salary has fallen and her nominal salary has risen. The correct option is C

Explanation:

NOMINAL SALARY is defined as the actual amount of money paid to a worker as compensation for work done monthly.

REAL SALARY or wages is defined as the quantity of goods and services an individual can purchase from a monthly income. Therefore it is affected by an increase or decrease in the general price level in an economy( inflation). For instance, if an individual nominal wage is increased by 10% and inflation is 0%( that is, there was no increase in price of goods in the market) then the individuals real wage is increased by 10% too. But if inflation is 10%, then the real wage will be 0% ( meaning the inflation is rising at the same rate with the nominal wage increase).

In the case of the professor, she had $200 increase in her monthly nominal wage and she can buy fewer number of goods and services than she bought last year(increased inflation). Therefore her real salary has fallen because even with the $200 increase, she couldn't buy her usual quantity of goods.

5 0

3 years ago