A downed pilot fires a flare from a flare gun. The flare an initial speed of 250 m/s and is fired at an angle of 35° to the grou
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Answer:
the direction of rate of change of the momentum is against the motion of the body, that is, downward.
The applied force is also against the direction of motion of the body, downward.
Explanation:
The change in the momentum of a body, if the mass of the body is constant, is given by the following formula:
p: momentum
m: mass
: change in the velocity
The sign of the change in the velocity determines the direction of rate of change. Then you have:
v2: final velocity = 35m/s
v1: initial velocity = 40m/s
Hence, the direction of rate of change of the momentum is against the motion of the body, that is, downward.
The applied force is also against the direction of motion of the body, downward.
Remember the definition of work done.
Work done is force(F) times displacement(x)
∴ W = F.Δx
According to Newton's 2nd law of motion,
F = ma
∴ W = ma.Δx ---- (i)
Using the kinematical equation v²-u² = 2ax,
aΔx = (v²-u²)/2
Plug this value in (i),
∴W = m[
]
∴W =
Which is nothing but change in kinetic energy.
That is how kinetic energy is derived
Work done is force(F) times displacement(x)
∴ W = F.Δx
According to Newton's 2nd law of motion,
F = ma
∴ W = ma.Δx ---- (i)
Using the kinematical equation v²-u² = 2ax,
aΔx = (v²-u²)/2
Plug this value in (i),
∴W = m[
∴W =
Which is nothing but change in kinetic energy.
That is how kinetic energy is derived