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padilas [110]
4 years ago
6

A car is travelling at constant velocity. Its brakes are then applied, causing uniform deceleration. Which graph shows the varia

tion with distance s of the velocity v of the car?
I want an answer ASAP and with explanation

Physics
1 answer:
Strike441 [17]4 years ago
6 0
First, note that all these graphs are velocity vs distance graphs. 
Therefore, you need to find a relation that explains how velocity changes with distance.

In a uniformly decelerated motion we have:
s = v₀·t - 1/2·a·t²
v = v₀ - a·t

Solve the first equation for t:
t = [v₀ +/- √(v₀²-2·a·s)] / a
For our purpose what is most important is the dependace:
t ∝ √-s

Now, substitute in the second equation, and we get:
v ∝ <span>√-s

Hence, the graph representing a radical function of a negative value is A).
</span>

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A cosmic-ray electron moves at perpendicular to earth’s magnetic field at an altitude where the field strength is. what is the r
Harlamova29_29 [7]

4.266 m is the radius of the circular path the electron follows.

Given

Speed of electron (v) = 7.5 × 10⁶ m/s

Earth's Magnetic Field (B) = 1 × 10⁻⁵ T

We already know that

Mass of electron (m) = 9.1 × 10⁻³¹ kg

Charge on electron (q) = 1.6 × 10⁻¹⁹ C

According to the formula

Radius of circular path(r) = mass on electron × speed/ Charge × Magnetic field

Radius of circular path(r) = m × v/q × B

Put the values into the formula

r = 9.1 × 10⁻³¹ × 7.5 × 10⁶/ 1.6 × 10⁻¹⁹ × 10⁻⁵

On solving, we get

r = 4.266 m

Hence, 4.266 m is the radius of the circular path the electron follows.

Learn more about magnetic field here brainly.com/question/26257705

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6 0
2 years ago
if a car has a kinetic energy of 400 J at 20m/s what.is the cars kinetic energy in kJ at a speed of 5 m/s
Nutka1998 [239]

Kinetic energy is an expression of the fact that a moving object can do work on anything it hits; it quantifies the amount of work the object could do as a result of its motion. It can be calculated as:

 

KE = mv^2 /2

 

We calculate the problem as follows:

 

KE = mv^2 /2

400 = m(20)^2 / 2

<span>m = 2 kg</span>

8 0
3 years ago
A horse running at 38 m/s reduces to 12 m/s in 10 seconds. What is the horse’s acceleration?
telo118 [61]
Never gonna give you up
Never gonna let you down
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8 0
3 years ago
A steel column is 3 m long and 0.4 m diameter. It carries a load of 50 MN so that 5.967 mm is elongates more. Find the modulus o
Alex787 [66]

Answer:

E=2.0*10^{11}N/m^{2}

Explanation:

<u>Relation between stress and Force:</u>

\sigma=\frac{F}{A}=\frac{F}{\pi*d^{2}/4}

<u>Relation between stress and strain:</u>

Young's modulus is defined by the ratio of longitudinal stress σ , to the longitudinal strain ε:

E=\frac{\sigma}{\epsilon}

\epsilon=\frac{\Delta l}{l}

So:

E=\frac{F*l}{\pi*d^{2}/4*\Delta l}=\frac{50*10^{6}*3}{\pi*(0.4^{2}/4)*5.967*10^{-3}}=2*10^{11}N/m^2

8 0
3 years ago
If the rods with diameters and lengths listed below are made of the same material, which will undergo the largest percentage len
seraphim [82]

Answer:

The highest percentage of change corresponds to the thinnest rod, the correct answer is a

Explanation:

For this exercise we are asked to change the length of the bar by the action of a force applied along its length, in this case we focus on the expression of longitudinal elasticity

               F / A = Y ΔL/L

where F / A is the force per unit length, ΔL / L is the fraction of the change in length, and Y is Young's modulus.

In this case the bars are made of the same material by which Young's modulus is the same for all

              ΔL / L = (F / A) / Y

the area of ​​the bar is the area of ​​a circle

               A = π r² = π d² / 4

               A = π / 4 d²

we substitute

              ΔL / L = (F / Y) 4 /πd²

changing length

               ΔL = (F / Y 4 /π) L / d²

The amount between paracentesis are all constant in this exercise, let's look for the longitudinal change

a) values ​​given d and 3L

               ΔL = cte 3L / d²

               ΔL = cte L /d²  3

To find the percentage, we must divide the change in magnitude by its value and multiply by 100.

                ΔL/L % = [(F /Y  4/π 1/d²) 3L ] / 3L 100

                ΔL/L  % = cte 100%

 

b) 3d and L value, we repeat the same process as in part a

               ΔL = cte L / 9d²

               ΔL = cte L / d² 1/9

               ΔL / L% = cte 100/9

               ΔL / L% = cte 11%

   

c) 2d and 2L value

               ΔL = (cte L / d ½ )/ 2L

               ΔL/L% = cte 100/4

               ΔL/L% = cte 25%

d) value 4d and L

               ΔL = cte L / d² 1/16

                ΔL/L % = cte 100/16

                ΔL/L % = cte 6.25%

   

The highest percentage of change corresponds to the thinnest rod, the correct answer is a

5 0
3 years ago
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