# An object is thrown vertically from a height of #12 m# at # 1 m/s#. How long will it take for the object to hit the ground?

##### 2 Answers

time

#### Explanation:

God bless...I hope the explanation is useful.

#### Explanation:

Assuming that the object is thrown upwards and then falls down, we can use one of the kinematic equations to solve for the time it takes for the object to hit the ground.

For the given problem, we will let positive values represent a downward direction.

#Deltad=12m#

#v_i=-1m/s#

#a=9.81m/s^2#

#Deltat=?#

Use the kinematic equation,

#Deltad=v_iDeltat+1/2aDeltat^2#

#0=1/2aDeltat^2+v_iDeltat-Deltad#

Plug in the values.

#0=color(darkorange)(1/2(9.81m/s^2))Deltat^2+(color(teal)(-1m/s))Deltat# #color(violet)(-12m)#

Use the quadratic formula to solve for

#x=(-b+-sqrt(b^2-4ac))/(2a)#

#x=(-(color(teal)(-1m/s))+-sqrt((color(teal)(-1m/s))^2-4(color(darkorange)(1/2(9.81m/s^2))(color(violet)(-12m)))))/(2(color(darkorange)(1/2(9.81m/s^2))))#

#x=1.67scolor(white)(i),color(white)(i)color(red)cancelcolor(black)(-1.47s)#

Since we are looking for the time it takes for the object to hit the ground **after** it is thrown, we take the positive value,

By rounding