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3 years ago

Which of the following frictionless ramps (A, B, or C) will give the ball the greatest speed at the bottom of the ramp? Explain.

Physics

1 answer:

Elenna [48]3 years ago

8 0

Let the ball is initially at point P1. Finally it reaches at point P2.( bottom most). Since only conservative force is acting on the ball throughout the motion, mechanical energy will be conserved. Therefore conserving energy from P1 to P2, Initially ball is at rest(P1). So initial kinetic energy is 0. Let ball is at height h1 initially, so initial potential energy = mgh ( m= mass of the ball). At bottom most point (P2), potential energy of ball changes into kinetic energy. So final kinetic energy =1/2 mv^2. Final potential energy = 0. Equating energies at P1 and P2, Mgh= 1/2 mv^2. Therefore, v= (2gh)^1/2. Since all the initial and final points are at same height, velocity will be same for all the paths(irrespective of the path taken by ball). So velocity will be same.

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A car initially at rest accelerates at 10m/s^2. The car’s speed after it has traveled 25 meters is most nearly... A.) 0.0m/s B.)

STALIN [3.7K]

The car traverses a distance $x$ after time $t$ according to

$x=\dfrac12at^2$

where $a$ is its acceleration, 10 m/s^2. The time it takes for the car to travel 25 m is

$25\,\mathrm m=\left(5\dfrac{\rm m}{\mathrm s^2}\right)t^2\implies t=\sqrt 5\,\mathrm s$

5 is pretty close to 4, so we can approximate the square root of 5 by 2. Then the car's velocity $v$ after 2 s of travel is given by

$v=\left(10\dfrac{\rm m}{\mathrm s^2}\right)(2\,\mathrm s)\approx20\dfrac{\rm m}{\rm s}$

which makes C the most likely answer.

3 0

3 years ago

Objects that transmit some light and reflect/absorb the rest of the light, like stained glass, are

11111nata11111 [884]

You are correct it is translucent because opaque let’s no light through but transparent lets almost all light through

3 0

3 years ago

Given the following specific heat capacities, which material was have the largest change in temperature if 10 grams of each subs

Ilya [14]

Answer:

Explanation:

Comment

You could calculate it out by assuming the same starting temperature for each substance. (You have to assume that the substances do start at the same temperature anyway).

That's like shooting 12 with 2 dice. It can be done, but aiming for a more common number is a better idea.

Same with this question.

You should just develop a rule. The rule will look like this

The greater the heat capacity the (higher or lower) the change in temperature.

The greater the heat capacity the lower the change in temperature

That's not your question. You want to know which substance will have the greatest temperature change given their heat capacities.

Answer

lead. It has the smallest heat capacity and therefore it's temperature change will be the greatest.

5 0

2 years ago

Read 2 more answers

Can someone help me on question 1?

grigory [225]

In question 1, both of your answers are correct, but I don't understand the process you went through in the 'a' part.

R = v/I . That's a correct formula.
But it doesn't help you in this form, because you need to find I
So turn it into a helpful form ... Solve it for I, so it says I=something.

R= v/I

Multiply each side by I : R I = V.

Now divide each side by R: I= V/R .
THERE'S the equation you want.

I = V / R

I = 1.5 / 10 = 0.15 Amp.

That's slightly cleaner, although I don't really understand what you were actually thinking in that part.

But again ... You answered both parts correctly, and your process in b is fine.

6 0

3 years ago

A rock thrown with speed 12.0 m/s and launch angle 30.0 ∘ (above the horizontal) travels a horizontal distance of d = 15.5 m bef

Dimas [21]

Supposing there's no air resistance, horizontal velocity is constant, which makes it very easy to solve for the amount of time that the rock was in the air.

Initial horizontal velocity is: 
cos(30 degrees) * 12m/s = 10.3923m/s

15.5m / 10.3923m/s = 1.49s

So the rock was in the air for 1.49 seconds.

Now that we know that, we can use the following kinematics equation:

d = v i * t + 1/2 * a * t^2

Where d is the difference in y position, t is the time that the rock was in the air, and a is the vertical acceleration: -9.80m/s^2.

Initial vertical velocity is sin(30 degrees) * 12m/s = 6 m/s

So:

d = 6 * 1.49 + (1/2) * (-9.80) * (1.49)^2
d = 8.94 + -10.89

d = -1.95

This means that the initial y position is 1.95 m higher than where the rock lands.

5 0

3 years ago