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3 years ago

Driving at a safe speed is particularly important because kinetic energy __________.

1 answer:

5 0

The correct answer is
<span>b. increases with the square of speed

In fact, the kinetic energy of a moving object is given by
</span> $K= \frac{1}{2}mv^2$
<span>where m is the mass of the object and v is its speed. We see that the kinetic energy is directly proportional to the square of the speed, therefore option B is the correct one.</span>

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How much energy is needed to change 100 g of 0o C ice to 0o C water? The latent heat of fusion for water L=335,000 J/kg. Hint: T

pychu [463]

Answer:

33.5 kJ

Explanation:

here there is no difference is made in the temperature. Only thing happens here is the conversion of the ice in to water of 0 degree. The heat energy taken from the outside is spent for this conversion.

we have ice 100g =0.1 kg

Appplying Q=mL

Q= $0.1 kg * 335 000 J kg^{-1}$

Q = 33 500 J

Q = 33.5 kJ

3 0

4 years ago

If carbon has an atomic number of 6, how many protons and neutrons are found in the carbon-14 atom? A.

Alex Ar [27]

The correct answer is B. 6 protons and 8 neutrons

Carbon-14 has same atomic number of 6. It has a nucleon number of 14
Atomic number = proton number = 6
Neutron number = nucleon number - atomic number = 14 - 6 = 8

Hope it helped!

5 0

4 years ago

The paper dielectric in a paper-and-foil capacitor is 0.0800 mm thick. Its dielectric constant is 2.50, and its dielectric stren

jeka94

Answer:

a) 0.723 m²

b) 2000V

Explanation:

Given that

Thickness of the capacitor, d = 0.08*10^-3 m

Dielectric constant of the capacitor, k = 2.5

Dielectric strength of the capacitor, E = 50*10^6

Capacitance of the capacitor, C = 0.2*10^-6

Permittivity of free space, E• = 8.85*10^-12

The area, A is given by the formula

A = (C * d) / (k * E•)

A = (0.2*10^-6 * 0.08*10^-3) / (2.5 * 8.85*10^-12)

A = 1.6*10^-11 / 2.213*10^-11

A = 0.723 m²

Potencial difference, V is given by the formula

V = E * d

V = 1/2 * 50*10^6 * 0.08*10^-3

V = 1/2 * 4000

V = 2000 V

8 0

4 years ago

A ball is kicked from the top of a building with a velocity of 50 m/s and lands 165 m away from the base of the building.

Nadusha1986 [10]

The height of the building is 53.4 m (projectile motion)

Explanation:

The motion of the ball is a projectile motion, so it follows a parabolic path which consists of two independent motions:

- A uniform motion (constant velocity) along the horizontal direction

- An accelerated motion with constant acceleration (acceleration of gravity) in the vertical direction

First of all, we consider the horizontal motion, which is a uniform motion at constant speed. The equation that gives the horizontal distance travelled is:

$d=v_x t$

where:

$v_x = 50 m/s$ is the horizontal velocity of the ball, which is constant since there are no forces in this direction

d = 165 m is the horizontal distance travelled by the ball

Solving for t, we find the time of flight:

$t=\frac{d}{v_x}=\frac{165}{50}=3.3 s$

Now we analyze the vertical motion: it is an accelerated motion, we can use the suvat equation

$s=ut+\frac{1}{2}at^2$

where

s is the vertical displacement, which is the height of the building

u = 0 is the initial vertical velocity of the ball

t = 3.3 s is the time of flight

$a=g=9.8 m/s^2$ is the acceleration of gravity

Solving for s, we find the height of the building:

$s=0+\frac{1}{2}(9.8)(3.3)^2=53.4 m$

Learn more about projectile motion here:

brainly.com/question/8751410

#LearnwithBrainly

6 0

4 years ago

An 870 N firefighter, F_ff, stands on a ladder that is 8.00 m long and has a weight of 355 N, F_ladder. The weight of the ladder

castortr0y [4]

Answer:

Explanation:

Weight of the ladder is 355N

WL = 355N

The weight of the ladder acts at center of the ladder I.e at 4m from the bottom

Weight of firefighters is 870N

Wf = 870N

The fire fighter is at 6.3m from the bottom of the ladder.

N1 is the normal force exerted by the wall

N2 is the normal force exerted by the ground

Using Newton law

Check attachment

ΣFy = 0, since body is in equilibrium

N₂ - WL - Wf = 0

N₂ = WL + Wf

N₂ = 870 + 355

N₂ = 1225 N

This the normal force exerted by the ground on the wall.

Now to get N₁, let take moment about point A

So, before we take the moment we need to make sure that the forces are perpendicular to the plane(ladder), we need to resolve the weight of the ladder, firefighter and the normal of the wall to be perpendicular to the plane.

ΣMa = 0

Clockwise moment is equal to anti-clockwise moment

Moment Is the produce of force and perpendicular distance.

M = F×r

So,

WL•Cos50 × 4 + Wf•Cos50 × 6.3 —N₁•Sin50 × 8 = 0

355•Cos50 × 4 + 870•Cos50 × 6.3 =

N₁•Sin50 × 8

1825.52 + 3523.12 = 6.13N₁

6.13N₁ = 5348.64

N₁ = 5348.64/6.13

N₁ = 872.54 N.

The normal force exerted by the wall is 872.54N

5 0

3 years ago