PHYSICS
MIDDLE SCHOOL

Answer:

false

but it may be true only if you fall the heavier one first

Answer: In real life, heavier objects sometimes fall faster than light objects, but not because of gravity. Gravity makes all objects increase their speed at the same rate, regardless of how big they are.

HIGH SCHOOL

What are 5 Non-Examples of Density

I'm not sure if there is five examples, but one easy one is light.

MIDDLE SCHOOL

How many number of electron shells does calcium have ?

20 electrons and 2 valence electrons

20 electrons have calcium

HIGH SCHOOL

A winch system powered by a 7.2 volt motor is used to lift a 30 Newton load a distance of 2.5 meters. The motor's current rating is 370 milliamps. What is the efficiency of the electro-mechanical system if the time required to raise the load is 90 seconds?

The power transferred by the motor is equal to the product between the current and the voltage:

However, the power used by the winch system is less than this value. In fact, the work done is equal to the weight of the load times the distance through which it has been lifted:

And the power used by the system is the work done divided by the time taken:

Therefore, the efficiency of the system is given by the ratio between the useful power and the power in input:

However, the power used by the winch system is less than this value. In fact, the work done is equal to the weight of the load times the distance through which it has been lifted:

And the power used by the system is the work done divided by the time taken:

Therefore, the efficiency of the system is given by the ratio between the useful power and the power in input:

MIDDLE SCHOOL

A car initially traveling at 21.4 m/s accelerates at a rate of 4.4 m/s2 for 7.5 seconds. What is the final velocity of the car?

The car's final velocity is 11.6 m/s in the opposite direction.

HIGH SCHOOL

Which statement describes the relationship of voltage and current? Voltage is directly proportional to current because I = .

Voltage is inversely proportional to current because I = .

Voltage is directly proportional to current because I = VR.

Voltage is inversely proportional to current because I = VR.

By definition, of the law of ohm, we have to:

Where,

V: voltage

I: current

R: resistance

Therefore, we have that the relationship between voltage and current is proportional.

The proportionality constant for this case is the resistance.

For the current we have:

The proportionality constant for this case is the inverse of the resistance.

Answer:

A statement that describes the relationship of voltage and current is:

Voltage is directly proportional to current because I = V / R

Voltage is directly proportional to current because I=V/R

COLLEGE

Which part of a stream's sediment load moves the slowest?

The bed load moves the slowest from all the parts of the stream's sediment. It consists of particles suspended that are suspended and float around the bed. This part is the slowest in motion, as it rolls, and moves with the flow. The particles near the bed are not dissolved so they settle at the bottom and move with the stream.

MIDDLE SCHOOL

Describe the oceans and explain how the water cycle affects the salinity of the ocean

Well the ocean is... uh, salty! Alright all joking aside, the ocean is largest body of water in world, in fact it covers 3/4 of the entire world, but since it contains so much salt we can't drink it. Now the water cycle allows us to drink it, and here's how! The Sun evaporates the surface layer of the oceans, not a lot though, now since salt is a solid it can't be evaporated, this increases the salinity of the oceans. Now let's say a strong wind pushes the evaporated water (or water vapor) onto land. Next the water molecules bind together forming clouds. When the clouds get so heavy with water, they must release some of that unneeded water. They do it through rain. Then some of the rain rolls off of land and back into the oceans decreasing the salinity. This is known as run off.

i hope this answers your question!

i hope this answers your question!

COLLEGE

A 8.0 n force acts on a 0.70-kg object for 0.50 seconds. by how much does the object's momentum change (in kg-m/s)? (never include units in the answer to a numerical question.)

Given the force acting on the object, the change in its momentum is 4kg.m/s.

- Force;

- Mass;

- Time,

To determine the object's change in momentum, we use the Impulse Momentum Theorem:

The impulse applied to a body or matter is equal to the change in its momentum

Impulse = Change in Momentum

Where F is the force applied and is the elapsed time

Hence

We substitute our given values into the equation

Therefore, given the force acting on the object, the change in its momentum is 4kg.m/s.

Learn more; brainly.com/question/14471691

For Newton's second law, the force applied to an object is equal to the product between the mass of the object and its acceleration:

Rewriting the acceleration as the increment of velocity in a time : , F becomes

But given the definition of momentum: , then represents the momentum change. So we can rewrite F as

And re-arranging the formula we can calculate the value of the change in momentum:

Rewriting the acceleration as the increment of velocity in a time : , F becomes

But given the definition of momentum: , then represents the momentum change. So we can rewrite F as

And re-arranging the formula we can calculate the value of the change in momentum:

COLLEGE

Two objects (38.0 and 17.0 kg) are connected by a massless string that passes over a massless, frictionless pulley. The pulley hangs from the ceiling. Find (a) the acceleration of the objects and (b) the tension in the string.

Answer:

a) 3.7 m/s^2

b) 231.8 N

Explanation:

Let m1 be mass of the first object (m1 = 38.0 kg) and let m2 be the mass of the second object (m2 = 17.0 kg ). Let a be the acceleration of the two objects. Let F1 be the force of gravity exerted on m1 and F2 be the force of gravity exerted on m2. Let M = m1 +m2

a)

F1 = m1g and F2 = m2g

So Fnet = F1 + F2

Since the pulleys will move in different directions when accelerating...

Fnet = F1 - F2

M×a = m1g - mg2

M×a = g×(m1 -m2)

a = g×(m1 - m2)/M

a = 9.8×(38 - 17)/(38 + 17)

a = 3.7 m/s^2

b)

Looking at the part for m2

Fnet = T - m2g

-m2×a = T - m2g

T = m2(g - a)

T = 231.8 N