Question

A, ball is gentally dropped froam a height of 20 m. If its velocity increases uniformly at the rate of 10 m/s 2 , with what velocity will ir strike the ground ? After time Will it strike the ground?

Answer 1

Given,

Distance (s) = 20 m

Accelaration (a) = 10 m/s²

Initial Velocity (u) = 0 m/s

Final velocity (v) = ?

Time (t) = ?

We know,

v² - u² = 2as

v² - 0 = 2 * 10 * 20

v² = 400

v = √400

v = 20 m/s

And, 

v = u+at

20 = 0 + 10 * t

20 = 10 t

t = 2 second

∴ Striking velocity = 20 m/s

∴ Striking time = 2 second

Answer 2

ɢɪᴠᴇɴ

ɪɴɪᴛɪᴀʟ ᴠᴇʟᴏᴄɪᴛʏ(ᴜ) = 0 ᴍ/ꜱ

ᴀᴄᴄᴇʟᴇʀᴀᴛɪᴏɴ (ᴀ) = 10 ᴍ/ꜱ²

ᴛɪᴍᴇ(ꜱ) = 20 ᴍ

ᴡᴇ ᴋɴᴏᴡ

ᴠ² = ᴜ² + 2ᴀꜱ

ᴘᴜᴛᴛɪɴɢ ᴠᴀʟᴜᴇꜱ:

ᴠ² = 0² + 2 (10 x 20)

ᴠ² = 400

ᴠ = 20 ᴍ/ꜱ

ꜰᴏʀ ᴛɪᴍᴇ:

ᴠ = ᴜ + ᴀᴛ

ᴛ = ᴠ - ᴜ/ᴀ

ᴛ = (20-0)10

  = 20/10

  = 2

∴ ꜱᴛʀɪᴋɪɴɢ ᴠᴇʟᴏᴄɪᴛʏ = 20 ᴍ/ꜱ

∴ ꜱᴛʀɪᴋɪɴɢ ᴛɪᴍᴇ = 2 ꜱᴇᴄᴏɴᴅꜱ