Quiz 2 revision

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course Phy 201

6/26 4:00 pm

Reason out the quantities v0, vf, `dv, vAve, a, `ds and `dt: If an object’s velocity changes at a uniform rate from 11 cm/s to 15 cm/s as it travels 117 cm, then what is the average acceleration of the object? Using the equations which govern uniformly accelerated motion determine vf, v0, a, `ds and `dt for an object which accelerates through a distance of 117 cm, starting from velocity 11 cm/s and accelerating at .444 cm/s/s.

Average Velocity : (11 cm/s + 15 cm/s) / 2

= 13 cm/s

Change in time:

117 cm / 13 cm/s

= 9 s

Average Accleration = ‘dv / ‘dt

(4 cm/s )/ 9 s

= 4/9 cm/s^2

vf = 15 cm / sec (given)

v0 = 11 cm / sec (given)

a = .444 cm/s^2 (given)

‘ds = 117 cm (given)

‘dt = 9 sec (found)

2nd Question:

V0= 11 cm/s (given)

‘ds= 117 cm (given)

a = .444 cm/s/s (given)

dv= vf-v0

dv= 15 cm/s - 11 cm/s

dv= 4 cm/s

vAve= (v0+vf)/2

vAve= ( 11 cm/s + 15 cm/s)/2

vAve= 13 cm/s

‘dt= ds/vAve

Dt= 117 cm/ 13 cm/s

Dt= 9 s

Vf=?

vf^2 = v0^2 + 2 a `ds

vf^2 =( 11cm/s)^2 + 2 (.444cm/s/s)(117 cm)

vf^2= 122 cm/s + 103.9 cm/s

squart(vf)= squart [ 225.9 cm/s]

vf= 15 cm/s

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