PHYSICS
MIDDLE SCHOOL

Answer:

it is important so you can discover new materials or inhabitle planets in case anything happens to earth

HIGH SCHOOL

a spacecraft has a momentum of 20000kg * m/s, and a mass of 250 kg. What is the magnitude of its velocity

Just make divide 20,000Kg*m/s ÷250Kg=80 m/s

COLLEGE

A force of 100,000 N is applied to an iron bar with a cross-sectional area of 10 mm 3 20 mm and having a yield strength of 400 MPa and a tensile strength of 480 MPa. Determine (a) whether the bar will plastically deform; and (b) whether the bar will experience necking.

Answer:The Cross sectional area is 10mm x 20mm

A) Yes they will plastically deform

B)Yes the bar will experience necking

Explanation:

Calculating for tensile stress= Force/Area= 100000/(20 x 10)= 500N/mm2. Converting to MPa = 500N/mm2 x 1MPa/1N/mm2= 500MPa

A) since yield strength of 400MPa is less than obtained stress of 500Mpa, the bar will plastically deform

B) since the tensile strength is less than the obtained stress,the Bar will experience necking

HIGH SCHOOL

An out-of-control train is racing toward the Metropolis terminal train station - only Superman can help. The train has a mass of 75000 kg, and Superman has a mass of 115 kg. If the train has a velocity of 35 m/s, how fast does Superman have to fly in the opposite direction to stop it in a totally inelastic steel-Man-of-Steel collision?

Answer:

22826.09 m/s

Explanation:

From the law of conservation of momentum,

Sum of momentum before collision = sum of momentum after collision.

For an inelastic collision, the train and the superman have a common velocity

Note: For the superman to stop the train in an opposite direction, the common velocity after collision is zero, and such the total momentum after collision is zero

Therefore,

MU + mv = 0

MU = - mu............................................ Equation 1

Making u the subject of the equation

u = -MU/m......................................... Equation 2

Where M = mass of the train, U = initial velocity of the train, m = mass of the super man, u = initial velocity of the superman.

Given: M = 75000 kg, U = 35 m/s, m = 115 kg.

u = -(75000×35/115)

u = -22826.09 m/s

Note: The velocity is negative because the direction of the superman is opposite the direction of the train.

Hence the superman have to fly 22826.09 m/s in the opposite direction

MIDDLE SCHOOL

Is defined as a state of balance

A weight

B mass

C equilibrium

Answer:

Equilibrium

Explanation:

Weight is the force acting on an object.

Mass is the amount of particles of an object.

But equilibrium describes the state of balance.

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