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Allushta [10]
2 years ago
14

Explain why free fall acceleration near earths surface is constant

Physics
1 answer:
Naya [18.7K]2 years ago
4 0
Because gravity is constant 
<span>the only force acting in free-fall is gravity which points downward at 9.8 m/s</span>
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A 150 N boy rides a 60 N bicycle a total of 200 m at a constant speed. The frictional force against the forward motion of the bi
soldier1979 [14.2K]

Answer:

W = 7000 J

Explanation:

To solve this problem we use that the speed of the bicycle is constant, therefore its acceleration is zero

            F -fr = 0

            F = fr

where F is the force applied by the child

Work is defined by

           W = F. x

           W = F x cos θ

in this case the child's force is parallel to the movement, therefore the angle is zero and cos 0 = 1

           

let's calculate

           W = 35 200

           W = 7000 J

8 0
2 years ago
At an accident scene on a level road, investigators measure a car's skid mark to be 93 m long. It was a rainy day and the coeffi
USPshnik [31]

Answer:

u = 25 m/s

Explanation:

given,                                

length of skid = 93 m          

coefficient of friction = 0.35

final velocity = 0 m/s              

initial velocity = ?                        

force here is friction  f = μ mg

F = ma                                                

now com paring                      

-μ mg = m a                      

a = - μ g                    

a = - 0.35 x 9.8              

a = -3.43 m/s²

we know,              

v² = u² + 2 a s                        

0 = u² - 2 x 3.43 x 93                

u² = 637.98                    

u = 25.26 m/s                      

u = 25 m/s (two significant figure)

6 0
3 years ago
A 230-km-long high-voltage transmission line 2.0 cm in diameter carries a steady current of 1,100 A. If the conductor is copper
Molodets [167]

Answer:

28.23 years

Explanation:

I = 1100 A

L = 230 km = 230, 000 m

diameter = 2 cm

radius, r = 1 cm = 0.01 m

Area, A = 3.14 x 0.01 x 0.01 = 3.14 x 10^-4 m^2

n = 8.5 x 10^28 per cubic metre

Use the relation

I = n e A vd

vd = I / n e A

vd = 1100 / (8.5 x 10^28 x 1.6 x 10^-19 x 3.14 x 10^-4)

vd = 2.58 x 10^-4 m/s

Let time taken is t.

Distance = velocity x time

t = distance / velocity = L / vd

t = 230000 / (2.58 x 10^-4) = 8.91 x 10^8 second

t = 28.23 years

5 0
3 years ago
Read 2 more answers
To make the next delivery, Sam-I-Am goes 45 mi/h for 2 hours. How far did he travel in that time?
andrezito [222]

Hello =D

This problem is about cinematic

So

V = 45 mi/h

t = 2 h

Then

V= X/t

X = V*t

Then

X = (45)*(2)

X = 90 mi

Best regards

5 0
2 years ago
An experimental rocket designed to land upright falls freely from a height of 2.59 102 m, starting at rest. At a height of 86.9
aleksandr82 [10.1K]

Answer:

The acceleration required by the rocket in order to have a zero speed on touchdown is 19.96m/s²

The rocket's motion for analysis sake is divided into two phases.

Phase 1: the free fall motion of the rocket from the height 2.59*102m to a height 86.9m

Phase 2: the motion of the rocket due to the acceleration of the rocket also from the height 86.9m to the point of touchdown y = 0m.

Explanation:

The initial velocity of the rocket is 0m/s when it started falling from rest under free fall. g = 9.8m/s² t1 is the time taken for phase 1 and t2 is the time taken for phase2.

The final velocity under free fall becomes the initial velocity for the accelerated motion of the rocket in phase 2 and the final velocity or speed in phase 2 is equal to zero.

The detailed step by step solution to the problems can be found in the attachment below.

Thank you and I hope this solution is helpful to you. Good luck.

5 0
2 years ago
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