Question

hello...... please help​

Answer 1

12 ) (d) none of these

explanation : t = 5

                    a = 2(t - 1) = 2(5 - 1) = 8 m/s²

velocity = acceleration × time

v = 8 × 5 = 40 m/s

13 ) (a) : 2 s

explanation : length = 50 m

two train are moving opposite so relative velocity of train'a' and train'b' is

Tab = Ta - Tb

Tab = 10 - (-15) = 25 m/s

time = 50/25 = 2

14) (b) : 1/√2

explanation :

speed of elevator , v = 10 m/s

height at which coin drops , h = 2.5

speed of coin , u = ?

acceleration due to gravity , g = 10 m/s²

∴ -u² = 2gh

u = ±√(-2gh)

u = ± √-(2×10×2.5)

u = ± (-5√2)

u = 5√2 m/s  or -5√2 m/s speed never in negative.