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3 years ago

5. Sarah is standing 32.0 m away from Jason. If Sarah throws a snowball at a 45 degree

Physics

1 answer:

padilas [110]3 years ago

7 0

Answer:

Explanation:

If air resistance is ignored and assume UP and Toward Jason are the positive directions.

horizontal analysis

d = (vx₀)t

t = d/vx₀

horizontal analysis

0 = vy₀t + ½gt²

0 = vy₀(d/vx₀)+ ½g(d/vx₀)²

as vy₀ = v₀sin45 and vx₀ = v₀cos45 and are equal.

0 = d + ½g(d²/v₀²cos²45)

-d = ½g(d²/v₀²cos²45)

-dv₀² = ½g(d²/cos²45)

v₀² = -½g(d/cos²45)

v₀² = -½(-9.81(32.0/cos²45)

v₀² = 313.92

v₀ = 17.717787...

v₀ = 17.7 m/s

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A train car has a mass of 10,000 kg and is moving at +3.0 m/s. It strikes an identical train car that is at rest. The train cars

jolli1 [7]

Answer:1.5

Explanation:

Edg

7 0

3 years ago

Which of the statements concerning light are true? The speed of light is the same no matter what material it is traveling throug

wel

Answer:

The statements that are true concerning light are the last three statements:

Its propagation direction is perpendicular to both the electric field and the magnetic field.

It moves at a constant speed through a vacuum.

The speed of light in matter is less than the speed of light in a vacuum.

Explanation:

Light is electromagnetic waves.

The properties of the electromagnetic waves were established by James Clerk Maxwell.

They included that they are the result of the oscillation of a magnetic field in phase with an electric field which are always is always perpendicular to each other.

Also, the electromagnetic waves propagate at right-angles to the direction of both the magnetic and the electric field, meaning that they are a type of transverse wave.

Thus, the second statement ("Its propagation direction is parallel to both the electric field and the magnetic field") is false, and the fourth statement ("Its propagation direction is perpendicular to both the electric field and the magnetic field") is true.

On the other hand, it is a postulate of the special theory of relativity that the speed of light is a constant (absolute value) in vacuum: nothing can travel faster than what light travels in vacuum. Thus, the fifth statement, "It moves at a constant speed through a vacuum" is true.

About the speed of light in matter, it is always less than the speed of light in vacuum. Thus, the first statement, "the speed of light is the same no matter what material it is traveling through", and the third statement "the speed of light in matter is greater than the speed of light in a vacuum" are false; while the last statement, "the speed of light in matter is less than the speed of light in a vacuum" is true.

The explanation on why the speed of light is less in a medium than in vacuum is related with the fact that at nanoscopic level the waves suffer polarization which means deviations from the straighi path, which makes that the net straight propagation is slower.

8 0

3 years ago

I need help please, thank you!!!

stiks02 [169]

Answer:

135 mph

because 7+9=16

8 is left

if 7=40

9=50

then 8=45

add 40+50+45mph

=135

4 0

2 years ago

A small boat coasts at constant speed under a bridge. A heavy sack of sand is dropped from the bridge onto the boat. The speed o

Tju [1.3M]

Answer:

d. decreases

Explanation:

The law of conservation of momentum tells us that the sum of momenta before the collision is equal to the sum of momenta after the collision. The bag has no momentum as it falls onto the boat because its velocity is zero in the horizontal direction. But after it hits the boat, it's momentum increases while the momentum of the system remains the same. That means a component of the system must decrease somewhere else. And that component is the velocity, not the mass, of the boat.

7 0

3 years ago

A thermometer initially reading 212F is placed in a room where the temperature is 70F. After 2 minutes the thermometer reads 125

frez [133]

Answer:

91.3°F

Explanation:

Let T be the temperature of the thermometer at any time

T∞ be the temperature of the room = 70°F

T₀ be the initial temperature of the thermometer = 212°F

And m, c, h are all constants from the cooling law relation

From Newton's law of cooling

Rate of Heat loss by the cake = Rate of Heat gain by the environment

- mc (d/dt)(T - T∞) = h (T - T∞)

(d/dt) (T - T∞) = dT/dt (Because T∞ is a constant)

dT/dt = (-h/mc) (T - T∞)

Let (h/mc) be k

dT/(T - T∞) = -kdt

Integrating the left hand side from T₀ to T and the right hand side from 0 to t

In [(T - T∞)/(T₀ - T∞)] = -kt

(T - T∞)/(T₀ - T∞) = e⁻ᵏᵗ

(T - T∞) = (T₀ - T∞)e⁻ᵏᵗ

Inserting the known variables

(T - 70) = (212 - 70)e⁻ᵏᵗ

(T - 70) = 142 e⁻ᵏᵗ

At t = 2 minute, T = 125°F

125 - 70 = 142 e⁻ᵏᵗ

55/142 = e⁻ᵏᵗ

- kt = In (55/142) = In (0.3873)

- k(2) = - 0.9485

k = 0.4742 /min

At time t = 4 mins

kt = 0.4742 × 4 = 1.897

(T - 70) = 142 e⁻ᵏᵗ

e^(-1.897) = 0.15

T - 70 = 142 × 0.15 = 21.3

T = 91.3°F

7 0

3 years ago