There are (one can say) three coequal theories of motion for a single particle: newton's second law, stating that the total force on an object causes its acceleration; the work–kinetic energy theorem, stating that the total work on an object causes its change in kinetic energy; and the impulse–momentum theorem, stating that the total impulse on an object causes its change in momentum. in this problem, you compare predictions of the three theories in one particular case. a 4.00-kg object has velocity 7.00ĵ m/s. then, a constant net force 11.0î n acts on the object for 4.50 s. a) calculate the object's final velocity, using the impulse–momentum theorem. vf= m/s

vf = 14.2176 m/s

Explanation:

Given

m = 4 Kg

viy = 7.00 ĵ m/s

Fx = 11.0 î N

t = 4.5 s

vf = ?

Using the Impulse - Momentum Theorem, we have

F*Δt = m*Δv    ⇒  F*Δt = m*(vf - vi)

⇒    vf = (F*Δt + m*vi) / m

⇒    vf = (F*Δt + m*vi) / m

For x-component

⇒    vfx = (Fx*Δt + m*vix) / m = (11 N*4.5 s + 4 Kg*0 m/s) / (4 Kg)

⇒    vfx = 12.375 î m/s

For y-component

⇒    vfy = (Fy*Δt + m*viy) / m = (0 N*4.5 s + 4 Kg*7 m/s) / (4 Kg)

⇒    vfy = 7 ĵ m/s

Finally:

vf = √(vfx² + vfy²)

⇒   vf = √((12.375 m/s)² + (7 m/s)²)

⇒   vf = 14.2176 m/s

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