# 9.2.2 Speed and Acceleration, PT3 Focus Practice

 
           
 Question 4:
 Table below shows the distances travelled and the average speeds for four vehicles.
 
            
 Vehicle    Distance (km)      Average speed (km/h)      A     230      115      B      250     100      C      170      85      D      245      70  
 Which vehicles took the same time to complete the journey?
  
 Solution:    
                     Time taken for vehicle A=       230       115      =2 hours           Time taken for vehicle B=       250       100      =2    1    2       hours           Time taken for vehicle C=       170       85      =2 hours           Time taken for vehicle D=       245       60      =3    1    2       hours                     
 
 Thus, the vehicles A and C took the same time to complete the journey.
 
   
 
 
           
Question 5:
 
Mei Ling drives her car from Kuantan to Kuala Terengganu for a distance of 170 km for 2 hours. She then continues her journey to Kota Bahru and increases her speed to 100 kmh-1 for 45 minutes.

 Calculate the acceleration, in kmh-2, of the car.
 
 Solution:
                    Speed from Kuantan to Kuala Terengganu           =       170    2      =85     kmh       1                           Acceleration           =       Final speedInitial speed       Time taken                =       10085             45       60                      =20     kmh       2                         
 
 
 
 
           
Question 6:
 
Diagram shows the distance between K and L. A car moves from K to L with an average speed of 80 kmh-1. After rest for 1 hour 30 minutes, the car then returns to K. The average speed of the car from L to K increases 20%. If the car reaches K at 5 p.m., calculate the time the car starts its journey from K.
 
 
 Solution
 
                 The time taken from K to L           =       160       80                =2 hrs                      The average speed from L to K           =80×1.2           =96     kmh       1                           The time taken from L to K           =       160       96                =1    2    3       hrs                      The total time taken for the whole journey           =2+1    1    2      +1    2    3                =5    1    6       hrs           =5 hour 10 minutes The car starts its journey from K at 11:50 a.m.