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4 years ago

Velocity is:

Physics

1 answer:

Romashka-Z-Leto [24]4 years ago

4 0

Answer:

Explanation:

A is correct as Velocity includes the + and - signs, indicating the direction followed by the magnitude which is the speed.

B is Wrong. Velocity is displacement divided by time.

C Im not sure, Sorry..

D is wrong. Same explanation as B

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How does a blue object look under all colors of light

OverLord2011 [107]

The "blue" object would look the same. Say that this blue object is a square. That "square" is every color but blue. The only reason that you see it as "blue" is because what we call "blue", it the only color of light that bounces back at our eyes. Under all colors of light, especially simultaneously. This square or any shape for that matter would absorb the other colors of light, but the blue will be rejected. Therefore, we can only see what bounces back at our eyes, which is the color blue in this case.

Hope this helps, WyattMarine501

6 0

3 years ago

An object is projected at 25m/s from the top of a building of height 50m. At the same instant,another object is projected from t

docker41 [41]

A) The objects have the same vertical position after 2 seconds

B) The objects have same vertical position at y = 30.4 m (but they do not collide since they have different x-position)

Explanation:

The motion of the first object along the vertical direction is a uniformly accelerated motion, so we can write its position at time t using the following equation:

$y_1(t)=h+u_1 t + \frac{1}{2}gt^2$

where:

h = 50 m is the initial height

$u_1=0$ is the initial vertical velocity (the object is projected horizontally, so the vertical velocity is zero at the beginning)

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

So, its vertical position can be rewritten as

$y_1(t)=50-4.9t^2$

The position of object 2 instead can be written as

$y_2(t)=(u_2 sin \theta)t + \frac{1}{2}gt^2$

where

$u_2 sin \theta$ is the initial vertical velocity, where

$u_2 = 50 m/s$ is the initial velocity

$\theta=30^{\circ}$ is the angle of projection

Substituting, we get:

$y_2(t)=(50)(sin 30^{\circ})t+\frac{1}{2}(-9.8)t^2=25t-4.9t^2$

The two objects collide when their vertical position is the same, so:

$y_1(t)=y_2(t)\\50-4.9t^2 = 25t-4.9t^2$

And solving for t, we find:

$50=25t\\t= 2 s$

Note that this means that the two object at t = 2 s have the same vertical position: however, this is not true for the horizontal position.

In order to find the point where they collide, we have to substitute the time of the collision that we found in part A into one of the expressions of the vertical position.

Substituting into the expression of object 2, we find:

$y_2(t) = 25t-4.9t^2=25(2.0)-4.9(2.0)^2=30.4 m$

We can verify that at the same time, the vertical position of object 1 is the same:

$y_1(t)=50-4.9t^2=50-4.9(2.0)^2=30.4 m$

This means that the two objects have the same vertical position at 30.4 m.

However, in reality, the two objects do not collide. In fact, object 1 is moving in the horizontal direction with constant velocity

$v_{1x}=25 m/s$

So its horizontal position at t = 2.0 s is

$x_1(2.0)=v_{1x}t=(25)(2.0)=50 m$

While object 2 is moving in the horizontal plane with velocity

$v_{2x}=u_2 cos \theta=(50)(cos 30^{\circ})=43.3 m/s$

So its horizontal position at t = 2.0 s is

$x_2(2.0)=v_{2x}t=(43.3)(2.0)=86.6 m$

So in reality, the two objects do not collide, if they start from the same x-position.

Learn more about projectile motion:

brainly.com/question/8751410

#LearnwithBrainly

7 0

3 years ago

Action and reaction forces are described by which of Newton’s laws of motion?

nikdorinn [45]

Answer:

third

Explanation:

for every action there is an equal and opposite reaction

example

bouncing ball

ball receives a force from the ground due to collision

that same force causes the ball to bounce off the ground

first law:

inertia

example

stuff in space doesn't move unless its pushed

then it keeps going unless something stops it

second law

force = mass times acceleration

example

harder you push a cart the faster it goes

the less a cart weighs the faster a cart goes

studysmarterus

spacecenterorg

energywavetheory

5 0

3 years ago

Rubbing your hands together warms them by converting work into thermal energy. If a woman rubs her hands back and forth for a to

KATRIN_1 [288]

Answer:

0.178 °C

Explanation:

Given:

The frictional force, F = 48 N

Number of rubs, n = 18

Distance covered per rub, d = 7.16 cm = 0.0716 m

Total distance covered in 18 rubs, D = 0.0716 × 18 = 1.288 m

mass of the tissues warmed, m = 0.1 kg

Now,

Work done, W = Force × Displacement

W = 48 × 1.288 = 61.8624 J

Now,

Work done is the change in heat

W = ΔQ = 61.8624 J

also,

ΔQ = mCΔT

where, C is the specific heat

for human tissue, C = 3470 J/kg°C

thus,

61.8624 J = 0.1 × 3470 × ΔT

ΔT = 0.178 °C

Hence, the change in temperature is 0.178 °C

6 0

4 years ago

A block of cheese is resting on an incline.

andreev551 [17]

Answer:

The answer is diagram B I tried it out and it worked

Explanation:

4 0

3 years ago