Question

4. A racing car has a uniform acceleration of 4 m s2. What distance will it cover in 10 s after start?
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Answer 1

Answer:

Explanation:

Uniform acceleration a = 4 m/s²

Initial velocity u= 0 m/s

Time t = 10 sec.

Velocity v after 10 sec= u + a t = 0 m/s + 4 m/s² × 10 s =40 m/s.

We shall calculate the distance covered by all possible methods

Using Average Velocity:

Initial velocity u= 0 m/s

Final velocity v= 40 m/s

Average velocity= ½( u +v) = ½ ( 0+40)= 20 m/s

Time= 10 s

Distance covered in 10 s= av. vel. × time= 20m/s × 10s = 200 m

Using the relation s = u t+ ½ a t²

u = 0 m/s, a = 4 m/s², t= 10 sec.

s = 0×10 + ½ 4× 10² = 200 m

Using the relation v² - u² = 2 a s,

u = 0 m/s, v= 40 m/s, a= 4 m/s²

s = 1/2 a ( v² - u²)= 1/2×4 ( 40² - 0²) = 1/8(1600–0)= 1600/8= 200 m.

Answer 2

Answer:

Explanation:

a =4m/s2, t=10s.

using 2nd equation of motion we have

s=ut +1/2at2

s =0+0.5*4*10*10

s=200m