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9.0 Speed and Acceleration
9.1 Speed
9.1.1 Self Practice 9.1
1. a. Time = !"# %&
''.! %&/*
= 3 "+
!',
hours
= 3 hours 24 minutes
b. Time = +# %&
!-# %&/*
= .
'
hours
= 45 minutes
c. Time = "## &
!-" &//
= 4 seconds
2. a. Distance = 80 B1 !
-
C
= 120 DE
b. Distance = 343(4.5)
= 1 543.5 DE
c. Distance = 3(5.5)
= 16.5 minutes
d. Distance = 250 B
0
.
C
= 666 -
.
DE
3. Speed = !## &
!-.#, /
= 8.285 E/J
4. Time = -,- %&
0# %&/*
= 3.4 hours
= 3 hours 24 minutes
8 hours 30 minutes + 3 hours 24 minutes
= 11 hours 54 minutes
= 1154 hour
5. a. "# %&
! *1 = "#×! ### &
!×3# &45
= 833 !
.
E/ELM
b. #.0 &
! / = #.0÷! ### %&
!÷3#÷3# *
= 2.88 DE/h
c. !!# %&
! * = !!# %&
!×3# &45
= 1 "
3
DE/ELM
6. *Get a better visual understanding by sketching out and listing
the information given for the specific part of the route.
From the diagram above, S = 160 DE can be
determined.
Ipoh-Tapah: Time = 3# %&
!## %&/* = 0.6 hour
Ipoh-Kuala Lumpur: Time = --# %&
!!# %&/* = 2 hours
Tapah-Kuala Lumpur: Time = 2 – 0.6
= 1.4 hour
∴ Average speed at Tapah-Kuala Lumpur
= !3# %&
!.' *
= 114.29 DE/h
7. -".+ &
! / = -".+÷! ### %&
!÷3#÷3# *
= 93.24 DE/h
9.2 Acceleration
9.2.1 Self Practice 9.2
1. a. Acceleration = -N!-
'
= −2.5 ]E/J- (∴ True)
b. Acceleration = !-.N+#."
!
"
= 43.33 DE/h- (∴ False)
c. Acceleration = ,N#
#.,!
= 9.86 E/J- (∴ True)
d. Acceleration = 3#N0#
#."
= −40 DE/h- (∴ False)
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2. a. Acceleration = !!#N3#
.#÷3#
= 100 DE/h- b. Acceleration = '#N,#
"÷3#
= −360 DE/h- 3. Acceleration = !#N0
'
= 0.5 E/J- 4. Acceleration = ,"N!'"
0
= −8.75 ]E/J-
∴ Deceleration = 8.75 ]E/J-
*Negative value of acceleration means deceleration.
E.g., Acceleration = −5 V/W!, Deceleration = 5 V/W!
9.3 Generating Excellence
1. Uniform speed: Lift, clock, fan
Non-uniform speed: Waves, wind, mini bus
2. a. Acceleration = ""N'#
"÷3#
= 180 DE/h- b. Acceleration = ."N""
3÷3#
= −200 DE/h- c. Acceleration = '.N."
'÷3#
= 120 DE/h- 3.
a. Time = 'Y"
!0
= 0.5 hour
= 30 minutes
b. 6 hours 40 minutes + 30 minutes
= 7 hours 10 minutes
∴ Shu Mei reaches her school at 7:10 a.m.
4. a. g = 185 DE
10 hours 5 minutes – 9 hours 30 minutes
= 35 minutes
∴ h = 150 + 35 = 185 minutes
b.
c. Average speed = ."'
'#"÷3#
= 52.44 DE/h
5. a. Acceleration of green marbles
= !N#
-.3
= 0.385 m/min2
b. Purple marble will stop moving at 5.2 min.
c. The maximum speed of the green marble is
1 m/min.
d. The two marbles collide at 3 minutes.
6. Distance = 105 B
.#
3#C
= 52.5 DE