A boy is pulling a 150 kg crate with a force of 1150 N. If the crate experiences a frictional force of 490 N, find: a) The acceleration of the crate.

b) The normal force acting on the crate.

First, let's find the resultant, and applicate 2nd law of Newton using the resultant, so:

R = ma

F - Ff = ma

Data:

F = Force = 1150 N

Ff = Friction force = 490 N

m = Mass = 150 kg

a = Aceleraction = ?

Replacing according our data:

1150 N - 490 N = 150 kg * a

660 N = 150 kg * a

660 N / 150 kg = a

a = 4,4 m/s²   ← Aceleration of the object

The normal force IS NOT the resultant force, the normal force's the force between the ground and the object, in another words, is the weight of the object, and for the weight:

w = mg

w = 150 kg * 10 m/s²

w = 1500 N   ← Normal force between object and ground.

pretty sure it's false

it's when something is going so fast it makes a loud noise, breaking the sound barrier, for example: a jet makes a loud noise, not only cause of the jet but because they reached a point where they went so fast that you can year the noise from various parts, kinda like a police car, lets say the car was going   so fast that you hear the siren of the cop car right next to you, but the car is probably a mile a way, it's cos the siren was next to you a few seconds if you understand me