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a force can exist between two charged particles or objects even if they're as small as subatomic particles. between which of these would no force exist?

a) proton-proton
b) neutron-proton
c) proton-electron
d) electron-electron

Explanation:

By given, we know that "a force can exist between two charged particles or objects even if they're as small as subatomic particles".

Having said that, the pair of particles without a force is neutron-proton, basically because the neutron is not a charged particle.

According to physics, this two subatomic particles are held together by the forces exerted by quarks, which are smalles subatomic particles.

So, if you notice, the answer is deducted from the problem itself, because it mentioned about charged particles, and neutrons are not charged.

Therefore, the right answer is B.

the minimum constant speed at which she can catch the train is 2.7 m/s

given:

acceleration = 0.6

time = 4.5 s

to find:

velocity = ?

formula used:

from 1st kinematic equation we get,

v = u + at

u = initial speed of train = 0 m/s

v = final speed of the train

a = acceleration of the train

t = time

solution:

from 1st kinematic equation we get,

v = u + at

u = initial speed of train = 0 m/s

v = final speed of the train

a = acceleration of the train

t = time

v = 0 + (0.6 × 4.5)

v = 2.7 m/s

the minimum constant speed at which she can catch the train is 2.7 m/s

find the surface area of the sphere to the nearest square unit. use a calculator.

a. 254 in.2

b. 64 in.2

c. 127 in.2

d. 1,018 in.2