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2 years ago

A firefighter is trying to

Physics

2 answers:

VLD [36.1K]2 years ago

7 0

Kinetic Energy. Kinetic energy is any type of movement. Movement is what is needed to break through a door.

tino4ka555 [31]2 years ago

4 0

Answer:

he will use kinetic energy to break through the door

Explanation:

because kinetic energy is movement and force

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A woman steps in front of a child to keep him from running off. which term best describes this example? negative work positive w

lana [24]

Answer:

negative force

Explanation:

Here woman is applying the force to stop the child or to prevent him from running.

Here we know that the force applied by the woman is opposite to the motion of child but here the child is not displaced by this applied force but the child is only prevented his running.

So here the work done by the woman is zero as there is no displacement by this force.

But here we can say that the the force of woman is against the motion of child so here this force is opposite force and hence it is termed as negative force here.

so correct answer will be

negative force

4 0

3 years ago

Read 2 more answers

The buildup of plaque on the walls of an artery may decrease its diameter from 1.1 cm to 0.90 cm. The speed of blood flow was 17

natka813 [3]

Answer

Initial radius of the artery is (1.1 cm) / 2 = 0.55 cm

final radius of the artery is (0.90 cm) / 2 = 0.45 cm

initial velocity of the blood is 17 cm/s

Using equation of continuity is

A₁v₁=A₂v₂

π r₁² x v₁ = π r₂² x v₂

r₁² x v₁ = r₂² x v₂

0.55² x 17 =0.45² x v₂

v₂=25.39 cm/s

Bernoulli's equation is

$P_1 - P_2 = \dfrac{1}{2}\rho (v_2^2-v_1^2)$

rho is the density of blood = 1060 kg/m^3

$P_1 - P_2 = \dfrac{1}{2}\times 1060 \times (0.254^2-0.17^2)$

$P_1 - P_2 =18.87\ Pa$

6 0

3 years ago

A hydraulic lift raises a 4000 kg automobile when a 500N force is applied to the smaller piston. If the smaller piston has an ar

MariettaO [177]

Answer:

The cross-sectional area of the larger piston is 800 cm².

Explanation:

Given;

mass of the automobile, m = 4000 kg

force applied on the small piston, F₁ = 500 N

area of the smaller piston, A₁ = 10 cm²

load lifted by the larger piston, F₂ = 4000 x 10 = 40,000 N

Pressure experienced by each piston is given as;

$\frac{F_1}{A_1} = \frac{F_2}{A_2}$

Where;

A₂ is the cross-sectional area of the larger piston

$\frac{F_1}{A_1} = \frac{F_2}{A_2} \\\\A_2 = \frac{F_2A_1}{F_1} \\\\A_2 = \frac{40,000 \ \times\ 10}{500} \\\\A_2=800 \ cm^2$

Therefore, the cross-sectional area of the larger piston is 800 cm².

8 0

3 years ago

Human activities that impact the water cycle

xeze [42]

Answer:

Explanation:

A number of human activities can impact on the water cycle: damming rivers for hydroelectricity, using water for farming, deforestation and the burning of fossil fuels.

3 0

2 years ago

A 0.1 kg toy contains a compressed spring. when the spring is released the toy fly 0.45 m upwards from ground level before falli

trapecia [35]

The speed of the toy when it hits the ground is 2.97 m/s.

The given parameters;

mass of the toy, m = 0.1 kg

the maximum height reached by the, h = 0.45 m

The speed of the toy before it hits the ground will be maximum. Apply the principle of conservation of mechanical energy to determine the maximum speed of the toy.

P.E = K.E

$mgh_{max} = \frac{1}{2} mv_{max}^2\\\\gh_{max} = \frac{1}{2} v_{max}^2\\\\v_{max}^2= 2gh_{max}\\\\v_{max} = \sqrt{2gh_{max}}$

Substitute the given values and solve the speed;

$v_{max} = \sqrt{2\times 9.8 \times 0.45} \\\\v_{max} = 2.97 \ m/s$

Thus, the speed of the toy when it hits the ground is 2.97 m/s.

Learn more here: brainly.com/question/7562874

7 0

2 years ago