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Novosadov [1.4K]

2 years ago

13

In an emergency situation, firemen need to respond as quickly as possible. If a fireman is responding from the second floor, how

long will it take to slide down the 8 m pole to reach the truck bay?

1 answer:

rjkz [21]2 years ago

8 0

Answer:

4m/s

Explanation:

May be different considering how long the pole is and how heavy the firefighter is.

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Karolina [17]

I’m pretty sure the answer would be D, sorry if it’s not correct!

5 0

2 years ago

A circuit has a current of 2.4 A. The voltage is increased to 4 times its original value, while the resistance stays the same. H

9966 [12]

Answer:

Resistance will become 4 times the previous value

Explanation:

We have given current in the circuit i = 2.4 A

According to ohm's law current in the circuit is given by $I=\frac{V}{R}$

So $2.4=\frac{V}{R}$ ............eqn 1

Now voltage is increased to 4 times so new voltage = 4 V

And current in the circuit is same as 2.4 A

We have to fond the resistance so that after increasing voltage current will be same

So $2.4=\frac{4V}{R_{unknown}}$ ..........eqn 2

Dividing eqn 1 and 2

$1=\frac{V}{R}\times \frac{R_{unkown}}{4V}$

$R_{unknown}=4R$

So resistance will become 4 times the previous value

6 0

2 years ago

Read 2 more answers

A 50.0-kg projectile is fired at an angle of 30 degrees above thehorizontal with an initial speed of 1.20 x 102 m/s fromthe top

Advocard [28]

Answer:

a) Em₀ = 42.96 104 J , b) $W_{fr}$ = -2.49 105 J , c) vf = 3.75 m / s

Explanation:

The mechanical energy of a body is the sum of its kinetic energy plus the potential energies it has

Em = K + U

a) Let's look for the initial mechanical energy

Em₀ = K + U

Em₀ = ½ m v2 + mg and

Em₀ = ½ 50.0 (1.20 102) 2 + 50 9.8 142

Em₀ = 36 104 + 6.96 104

Em₀ = 42.96 104 J

b) The work of the friction force is equal to the change in the mechanical energy of the body

$W_{fr}$ = Em₂ -Em₀

Em₂ = K + U

Em₂ = ½ m v₂² + m g y₂

Em₂ = ½ 50 85 2 + 50 9.8 427

Em₂ = 180.625 + 2.09 105

Em₂ = 1,806 105 J

$W_{fr}$ = Em₂ -Em₀

$W_{fr}$ = 1,806 105 - 4,296 105

$W_{fr}$ = -2.49 105 J

The negative sign indicates that the work that force and displacement have opposite directions

c) In this case the work of the friction going up is already calculated in part b and the work of the friction going down would be 1.5 that job

We have that the work of friction is equal to the change of mechanical energy

$W_{fr}$ = ΔEm

$W_{fr}$ = Emf - Emo

-1.5 2.49 10⁵ = ½ m vf² - 42.96 10⁴

½ m vf² = -1.5 2.49 10⁵ + 4.296 10⁵

½ 50.0 vf² = 0.561

vf = √ 0.561 25

vf = 3.75 m / s

6 0

2 years ago

Akeem is walking on the beach on a hot summer day. The sand is very hot, so he runs and puts his feet in the water, which is muc

kramer

Sample Response: The water is cooler than the sand because it has a higher specific heat value. This means that it takes longer for the water to increase in temperature, making it feel cooler than the sand, which warms up more quickly.

4 0

2 years ago

Read 2 more answers

A block oscillating up and down on a spring comes to the top of its path, where it is momentarily at rest. At the instant it is

True [87]

Opposite to the direction of the velocity which led it to its current position.

Explanation:

The direction of momentum when a vertically oscillating block comes to the rest momentarily will be opposite to the direction of the velocity that it has just followed to reach reach its current position.

The direction of change in momentum at the bottom will be upwards and at the top will be downwards.

The change in momentum is mathematically defined as:

$\Delta P=m.v_f-m.v_i$

where:

$m=$ mass of the block

$v_f=$ final velocity of the block

$v_i=$ initial velocity of the block

When the block comes to rest it is due to the result of continuously decreasing velocity.

7 0

2 years ago