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faltersainse [42]
3 years ago
6

You don't need to push off with a foot against the ground to start

Physics
1 answer:
Angelina_Jolie [31]3 years ago
4 0

Answer:

No, it does not violate Newton's first law

Explanation:

Newton's first law of motion states that, "A body will continue in its state of rest or uniform motion in a straight unless acted up by a force to make it act otherwise" This means a force is required to initiate movement and also required to halt it.

For a skate positioned to roll down a bank, Here, the force of gravity acting on the skate acting downward will make the skate roll without having to push off the skate with a foot. Because the position of the skate doesn't balance the Gravitational force acting on it. Hence. The Gravitational force is enough to set the skate in motion.

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The velocity of a 640-kg auto is changed from 10.0 m/s to 44.0 m/s in 71.0 s by an external, constant force. (a) What is the res
n200080 [17]

Answer:

(a) <em>change in momentum of the car = 21760 kgm/s</em>

(b) <em>The magnitude of the force = 306.48 N</em>

Explanation:

<em>(a)</em>

<em>Change in momentum: </em><em>This is the product of mass and change in velocity. The unit of momentum is kgm/s. It can be expressed mathematically as,</em>

Change in momentum of the car = m(v-u)................. Equation 1

Where m = mass of the car, v = final velocity of the car, u = initial velocity of the car.

<em>Given: m = 640 kg, v = 44.0 m/s, u = 10.0 m/s.</em>

<em>Substituting these values into equation 1,</em>

<em>Change in momentum of the car = 640 (44-10)</em>

<em>change in momentum of the car = 640× 34</em>

<em>change in momentum of the car = 21760 kgm/s</em>

<em>change in momentum of the car = 21760 kgm/s</em>

<em>(b) Force:</em><em> Force of a body can be defined as the product of mass and its acceleration. It is measured in Newton (N). It can be expressed mathematically as,</em>

<em>Force = ma ................................ Equation 2</em>

<em> </em><em>    Or</em>

<em>Force = m(v-u)/t...................................... Equation 3</em>

<em>Where m = mass of the car, v = final velocity of the car, u = initial velocity of the car, a = acceleration of the car, t = time taken to change the velocity.</em>

<em>Given: m = 640 kg, u = 10.0 m/s v = 44 m/s, t = 71 s.</em>

<em>Substituting these values into equation 3</em>

<em>Force = 640(44-10)/71</em>

<em>Force = (640×34)/71</em>

<em>Force = 306.48 N</em>

<em>The magnitude of the force = 306.48 N</em>

3 0
3 years ago
What is the focal length of a lens? the distance between the object and the image distance between the object and the center of
maks197457 [2]
Distance between the focal point and the center of the lens
4 0
3 years ago
During an experiment, you take a measurement of 3.5 inches. What is this
raketka [301]
B. 8.89 (hope this helped.)
You can solve by just doing 3.5in * 2.54
4 0
4 years ago
Jack and jill exercise in a 25.0-m-long swimming pool. Jack swims nine lengths of the pool in 157.9 seconds (2 minutes and 37.9
bagirrra123 [75]

solution:

Average velocity

Average velocity is,

Here x is the displacement and t is the time.

At the end of swimming nine length of the pool, Jack reaches the other end of pool, hence the displacement x is the length of pool, that is 25.0 m. The total time taken, t is 157.9s.

Substitute 25.0 m for x and 157.9 s for t to calculate the average velocity. The average velocity of Jack is,

v_{a} =25.0m/157.9s

v_{a} =0.158m/s

At the end of swimming ten length of the pool, Jill reaches where he started, hence the displacement x is zero. The total time taken, t is 157.9s.

Substitute 0.00 m for x and 157.9s for t to calculate the average velocity. The average velocity of Jill is,

v_{a} =0m/157.9s

v_{a}= 0m/s

The average velocity of Jack is 0.158m/s and the average velocity of Jill is 0 m/s.

Average speed

Average speed is,

 

Here, d is the distance travelled and t is the time.

At the end of swimming nine length of the pool, distance travelled by Jack is nine times the length of pool; that is,

 

The total time taken, t is 157.9s.

Substitute 225 m for d and 157.9 s for t to calculate the average speed. The average speed of Jack is,

s_{a} =225m/157.9s

1.58m/s

  =1.42m/s

 

At the end of swimming ten length of the pool, distance travelled by Jill is ten times the length of pool; that is,

 

The total time taken, t is 157.9s.

Substitute 250 m for d and 157.9s for t to calculate the average speed. The average speed of Jill is,

s_{a} =250m/157.9s

1.58m/s


7 0
4 years ago
Which optical devices spread light apart?
Harman [31]

\mathfrak{\huge{\pink{\underline{\underline{AnSwEr:-}}}}}

Actually Welcome to the Concept of the Optical Devices.

Now basically here the devices that can spread light over apart are the CONCAVE LENS and Convex mirror.

so the Answer is

C. B and D

4 0
3 years ago
Read 2 more answers
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