# NEED HELP IN THIS PROJECTILE MOTION QUESTION (1 Viewer)

#### Greninja340

##### Active Member
Could someone show me how to approach this question and other similar projectile motion questions

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#### idkkdi

##### Well-Known Member
Could someone show me how to approach this question and other similar projectile motion questions
find where the projectile is level with the cliff.
then, s = ut+1/2 at^2
50 - 10sin30t = ut+1/2at^2 (y-axis)
u get value of t from the point where the projectile is level with the cliff. v(x)t + distance of level with cliff point to cliff..

but that question is kinda retarded. since technically, the object could slide back down the slope if friction is not big enough.

#### idkkdi

##### Well-Known Member
find where the projectile is level with the cliff.
then, s = ut+1/2 at^2
50 - 10sin30t = ut+1/2at^2 (y-axis)
u get value of t from the point where the projectile is level with the cliff. v(x)t + distance of level with cliff point to cliff..

but that question is kinda retarded. since technically, the object could slide back down the slope if friction is not big enough.
oops, slight error with the t value, but methodology is fine. 10sin30t value is t + time to that point. rhs t value is just time from that point.

#### idkkdi

##### Well-Known Member
oops, slight error with the t value, but methodology is fine. 10sin30t value is t + time to that point. rhs t value is just time from that point.
ngl i made my answer way more complicated than it needs to be lol.

just equate
50+ut+1/2at^2 = 10sin30t
for the y axis to find value t.
then take 10cos45t.

#### cossine

##### Member
tan(30) = 1/sqrt(3)= opp/adj = rise/run

Setting the origin at the cliff the slope is given by (1/sqrt(3))*x -50 = y

The motion of the projectile is given by

(-g*x^2)/100 + x = y

Solve for x:

(1/sqrt(3))*x -50 = (-g*x^2)/100 + x

Remember to write down why one of the solutions was discarded.

• Velocifire, idkkdi and B1andB2

#### idkkdi

##### Well-Known Member
tan(30) = 1/sqrt(3)= opp/adj = rise/run

Setting the origin at the cliff the slope is given by (1/sqrt(3))*x -50 = y

The motion of the projectile is given by

(-g*x^2)/100 + x = y

Solve for x:

(1/sqrt(3))*x -50 = (-g*x^2)/100 + x