Question

11. A ball is thrown vertically upwards with a speed
68 m/s. The distance travelled by the ball in its
seventh second of motion will be (g = 10 m/s?]
(1) 10 m
(2) 2.1 m
(3) 3.4 m
(4) 5 m​

Answer 1

Answer:

s=ut +1/2gt2

s=0*7+1/2*10*7‛2

s=0+5*49

s =245m

Answer 2

$S_n=131.7\ m$ is the distance travelled by the ball in its  seventh second of motion.

Explanation:

We have the equation of motion for the distance travelled in the nth second:

$S_n=u+\frac{1}{2} a.(2n-1)$

Now we are given with:

initial velocity, $u=68\ m.s^{-1}$

the given time instant, $n=7^t^h \ s$

Putting respective values:

here a = g

$S_n=68+\frac{9.8}{2} (2\times 7-1)$

$S_n=131.7\ m$

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TOPIC: equation of motion

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