Question

An object is thrown vertically upwards and rises to a height of 10 m. calculate the velocity with which the object was thrown upwards? Take g=9.8 m/s2

a. 14m/s

b. 16m/s

c. 10m/s

d. 9.8 m/s

Q8.The time taken by the object to reach the highest point in the above question

a. 1.42s

b. 1.5 s

c. 1 s

d. 1.43 s

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Answer 1

Answer:

14m/s

Explanation:

7.

g=-9.8m/s2

h=10m

v=0

u=?

by 3rd equation of motion

v^2=u^2+2gh

0=?+2×-9.8×10

0=?-196

196=u^2

14=u

8.

first equation of motion

v=u+at

0=14-9.8t

t=14/9.8

t=1.42 s

Answer 2

An object is thrown vertically upwards and rises to a height of 10 m.

1. we have to calculate the velocity with which the object was thrown upwards.
2. the time taken by the object to reach the highest point in the above question.

1. let the initial velocity of object is u m/s.

final velocity of the object , v = 0 m/s. [ because at the highest point, it becomes rest ]

the height reached by the object , s = 10 m

using formula, v² = u² + 2as

here, a = -9.8 m/s²

⇒0² = u² + 2(-9.8)(10)

⇒u = 14 m/s

hence, option (a) 14 m/s , is correct.

2. using formula, v = u + at

here, u = 14 m/s , v = 0 , a = -9.8 m/s²

⇒0 = 14 - 9.8t

⇒t = 14/9.8 = 10/7 = 1.428 ≈ 1.43 sec

Therefore the time taken to reach the height is 1.43 s.

hence, option (d) is correct.