Question

Three objects have velocities that vary with time

Answer 1

See below ~

Step-by-step explanation:

Question 21 :

⇒ v = u + at

⇒ v = 5 + 1.3 (2)

⇒ v = 5 + 2.6

⇒ v = 7.6 m/s

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Question 22 : At t = 3

Subpart (a)

⇒ Object 1 : v = 2 + 3(3) = 11 m/s

⇒ Object 2 : v = -8 - 4(3) = -20 m/s

⇒ Object 3 : v = 1 - 5(3) = -14 m/s

⇒ Hence, their velocities are in the order : Object 2 < Object 3 < Object 1

Subpart (b)

⇒ Object 1 : v = | 2 + 3(3) | = 11 m/s

⇒ Object 2 : v = | -8 - 4(3) | = 20 m/s

⇒ Object 3 : v = | 1 - 5(3) | = 14 m/s

⇒ Hence, their speeds are in the order : Object 1 < Object 3 < Object 2

Answer 2

#21

• initial velocity=u=5m/s
• Time=t=2s
• Acceleration=a=1.3m/s²

According to first equation of kinematics

• v=u+at
• v=5+1.3(2)
• v=5+2.6
• v=7.6m/s

#22

#a

• v1=2+3(3)=2+9=11m/s
• v2=-8-4(3)=-20m/s
• v3=1-5(3)=-14m/s

The order is

• v2<V3<v1

#b

for speed find absolute velocity

• S1=|11|=11m/s
• S2=|-20|=20m/s
• S3=|-14|=14m/s

So order is

S1<S3<S2