Question

a body is projected at an angle of 30 to the horizontal with a speed of 30 ms^-1 .The angle made by the velocity vector with the horizontal after 1.5 seconds?
g = 10ms-2

Answer 1

meh

Answer 2

@imqwerty

Answer 3

Any ideas?

Answer 4

vector law of triangle addition?
maine isko resolve kiya

Answer 5

fir us grph ko copy karke x axis ko t leliya

Answer 6

fir 1.5 s pe 0 mila

Answer 7

wait..grph??

Answer 8

ans ryt h but kya yeh method ryt h?

Answer 9

graph**

Answer 10

Which graph??

Answer 11

30 ko resolve kiya

Answer 12

You mean that you resolved velocity into its x nd y components?

Answer 13

yes

Answer 14

Okay what next

Answer 15

now stuck

Answer 16

You got stuck here but still managed to get the answer?
Anyways assume the velocity in the direction of projection to be v

The x component will be vcos(30) which you know is equal to 30

Similarly find y component of velocity

Now x component of velocity will remain same cuz no force is acting in x direction but y component will keep changing due to gravity

Answer 17

Find the velocity in y direction at the given time

You already know the velocity in x direction
Now you can find the angle between velocity vector and the horizontal by using trigonometry

Answer 18

what the heck is wrong with your english Aaron xD

Answer 19

@welshfella

Answer 20

the angle is given as 30

Answer 21

how can vcos(30) be same as v?

Answer 22

vcos(30) = 30*sqrt3/2 = 15*sqrt3

Answer 23

horizontal component of the velocity = 30 cos 30 = 15sqrt3
vertical component = 30 sin 30 = 15 at the point of projection

the horizontal component is constant

Answer 24

at time 1.5 we can can find the vertical component by using
v = u - 10t ( im taking acceleration due to gravity to be 10ms-2)

v = 15 -10*1.5 = 0

Answer 25

hmm i did'nt expect that expect that
lets check my work

Answer 26

whats wrong?

Answer 27

a value of 0 means that the angle with the horizontal is 0. Its height is at its maximum

Answer 28

then can the angle be 0?

Answer 29

of course if we use the more accurate acc due to gravity it will be slightly different ( a = 9.81 ms-2)

Answer 30

Thanks,sir!
Can you please help with a few more questions?

Answer 31

did the question say what value of acc due to gravity to take?

Answer 32

g = 10

Answer 33

oh ok then 0 degrees is the right answer.

Answer 34

be back in 5 minutes

Answer 35

Thanks!
I have a few more questions i need help with/in..

can you please help more?