Question

a ball is thrown upward with initial velocity of 20 m/s it will attain height is​

Answer 1

Answer:

A ball is thrown upward with an initial velocity of 20 m/s. How long will it take for the ball to reach its maximum height? A ball is thrown downward from the top of a roof with a speed of 25 m/s.

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Time, t Velocity, Displacement

After 4 seconds -10 m/s 40 m

After 5 seconds -20 m/s 25 m

After 6 seconds -30 m/s

Answer 2

${\large{\pmb{\sf{\underline{RequirEd \: solution...}}}}}$

${\bigstar \:{\pmb{\sf{\underline{Understanding \: the \: question...}}}}}$

⋆ This question says that there is a ball and that ball is thrown upwards with an initial velocity 'u' that is of 20 metres per second. Now this question says that we have to find that how much height 'h' the ball attains. Let's solve this question!

${\bigstar \:{\pmb{\sf{\underline{Provided \: that...}}}}}$

⠀⠀⠀⠀⠀⠀A ball is thrown upward with initial velocity of 20 m/s, it will attain how much height?

$\sf According \: to \: statement \begin{cases} & \sf{Initial \: velocity \: = \bf{20 \: m/s}} \\ \\ & \sf{Final \: velocity \: = \bf{0 \: m/s}} \\ \\ & \sf{Height \: = \bf{?}} \end{cases}$

Don't be confused! Final velocity came as zero because ball is attaining height.

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${\bigstar \:{\pmb{\sf{\underline{Diagram \: regards \: question...}}}}}$

$\setlength{\unitlength}{1mm}\begin{picture}(7,2)\thicklines\multiput(7,2)(1,0){55}{\line(3,4){2}}\multiput(35,7)(0,4){12}{\line(0,1){0.5}}\put(10.5,6){\line(3,0){50}}\put(35,60){\circle*{12}}\put(37,7){\large\sf{u = 20 m/s}}\put(37,55){\large\sf{v = 0 m/s}}\put(21,61){\large\textsf{\textbf{Ball}}}\put(43,40){\line(0, - 4){28}}\put(43,35){\vector(0,4){18}} {\pmb{\sf{BrainlyButterfliee}}}\put(24, - 3){\large\sf{ \sf g = -9.8 m/s^2 }}\put(48,30){\large\sf{H = ?}}\end{picture}$

Don't think so! What is g here? It is acceleration due to gravity.

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${\bigstar \:{\pmb{\sf{\underline{Knowledge \: required...}}}}}$

⋆ The acceleration due to gravity is always given by 9.8 m/s²

⋆ Why we use negative sign for g as it is always positive 9.8 m/s sq.?

We are taking it as negative because of the following reasons:

• Acceleration due to gravity is 9.8 m/s²

⠀⠀⠀⠀⠀⠀⠀⠀⠀⠀But

• Acceleration of an object is -9.8 m/s² whenever it is in upward motion.

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${\bigstar \:{\pmb{\sf{\underline{Using \: concepts...}}}}}$

⋆ To solve this question we have to take the help of an equation of motion that is Equation 3 (v² = u² + 2as) From this formula, the given formula is derived and here we have to imply it. The suitable using formula is mentioned:

⠀⠀⠀⠀⠀⠀⠀⠀${\small{\underline{\boxed{\sf{\longrightarrow v^{2} - u^{2} \: = 2gh}}}}}$

(Where, v denotes final velocity, u denotes initial velocity, g denotes acceleration due to gravity and h denotes height)

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${\bigstar \:{\pmb{\sf{\underline{Solution...}}}}}$

$:\implies \sf v^{2} - u^{2} \: = 2gh \\ \\ :\implies \sf (0)^{2} - (20)^{2} \: = 2(-9.8)(h) \\ \\ :\implies \sf 0 - 400 \: = 2(-9.8h) \\ \\ :\implies \sf -400 \: = -19.6h \\ \\ :\implies \sf \not{-}400 \: = \not{-}19.6h \\ \\ :\implies \sf 400 \: = 19.6h \\ \\ :\implies \sf \dfrac{400}{19.6} \: = h \\ \\ :\implies \sf 20.40 = h \\ \\ :\implies \sf h = 20.40 \\ \\ :\implies \sf Height \: = 20.40 \: metres \\ \\ {:\implies{\underline{\boxed{\pmb{\sf{\red{Height \: attained \: is \: 20.40 \: metres}}}}}}}$