An aeroplane lands on a runway at a speed of 180 km/hr and it's brought to a stop uniformly in 30 seconds. What distance does it cover on the runway before coming to rest?

John Perolski
August 07, 2023

 Physics Jamb, Waec, Neco Past Questions & Answers on Speed, Velocity and Acceleration 


Question 18. An aeroplane lands on a runway at a speed of 180 km/hr and it's brought to a stop uniformly in 30 seconds. What distance does it cover on the runway before coming to rest?  A 360m B. 540m C. 750m D. 957m

JAMB 1993 Ans 750m 


Solution;

Initial Speed or velocity u = 180km/hr => 180 x 1000m/3600 = 180,000/3600 = 1800/36/= 50m/s
Final velocity v = 0m/s
Time t = 30s 
Distance s =? 
Acceleration a= ?

Using the first equation of motion to find acceleration a 

v= u + at
0 = 50 + a(30)
0 = 50 + 30a
30a = 0-50
a = 50/-30 
a = -1.67m/s²

Using the second equation of motion to find distance s

S = ut + ½ at²
S = 50(30) + ½ (-1.67)(30)²
S = 1500 + ½ x -1.67 x 900
S = 1500 + ½ x -1503
S = 1500 - 751.5
S = 748.5m ≈ 749m or 750m Answer