A car starts from the rest and accelerates at the rate of 5m/s2. It continue accelerating for 10 s and then move at constant velocity for next 10 s. Calculate the total distance traveled by the car in 20s. (5)

 

Asked by siddsag2972 | 11th May, 2020, 12:48: PM

Expert Answer:

a = 5 m/s2 
u =0
v =?
 
Distance covered by car when it was still accelerating in for 10 s is given by 2nd equation of motion, 
 
s = ut + 1/2 at2 
 
s subscript 1 space equals u t subscript 1 space plus space 1 half a t subscript 1 superscript 2 space
equals space 0 space plus space 1 half cross times left parenthesis 5 right parenthesis space open parentheses 10 close parentheses squared space
s subscript 1 equals space 250 space m space
Now, it attains a constant speed. This constant speed can be calculated using first equation of motion, 
 
v = u + at 
v = 0 + (5) x (10) 
v = 50 m/s 
 
Now, let's calculate the distance travelled in next 10 s. 
As the velocity attains the constant velocity, the acceleration will become zero. 
 
Hence, 
 
s subscript 2 space equals u t subscript 2 space plus space 1 half a t subscript 2 superscript 2 space
equals space 50 space cross times space left parenthesis 10 right parenthesis space plus space 1 half cross times left parenthesis 0 right parenthesis space open parentheses 10 close parentheses squared space
s subscript 2 equals space 500 space m space

 
Thus, the total distance covered in these 20 s = s1 + s2 = 250 + 500 = 750 m 
 

Answered by Shiwani Sawant | 11th May, 2020, 04:10: PM