# projectiles Watch

Announcements

Page 1 of 1

Go to first unread

Skip to page:

a golf ball is struck at a point O on the ground and moves with an initial velocity of 20ms-1 at an angle of 53* to the horizontal. the ball subsequently lands at a point x which is on the same horizontal level as O.

for parts and b i worked out the time to reach point x is 3.26 and the distance between O and X is 39.2m

however i dont undestand part c

ci. state the least speed of the ball during its flight from 0 to X

cii. state the direction of motion of the ball when this least speed occurs

please explain, thanks!

for parts and b i worked out the time to reach point x is 3.26 and the distance between O and X is 39.2m

however i dont undestand part c

ci. state the least speed of the ball during its flight from 0 to X

cii. state the direction of motion of the ball when this least speed occurs

please explain, thanks!

0

reply

Report

#2

(Original post by

a golf ball is struck at a point O on the ground and moves with an initial velocity of 20ms-1 at an angle of 53* to the horizontal. the ball subsequently lands at a point x which is on the same horizontal level as O.

for parts and b i worked out the time to reach point x is 3.26 and the distance between O and X is 39.2m

however i dont undestand part c

ci. state the least speed of the ball during its flight from 0 to X

cii. state the direction of motion of the ball when this least speed occurs

please explain, thanks!

**Chez 01**)a golf ball is struck at a point O on the ground and moves with an initial velocity of 20ms-1 at an angle of 53* to the horizontal. the ball subsequently lands at a point x which is on the same horizontal level as O.

for parts and b i worked out the time to reach point x is 3.26 and the distance between O and X is 39.2m

however i dont undestand part c

ci. state the least speed of the ball during its flight from 0 to X

cii. state the direction of motion of the ball when this least speed occurs

please explain, thanks!

c.ii. Once you figure out WHEN precisely this minimum vertical velocity occurs (not in terms of time, but in terms of the motion) then it should be fairly obvious in what direction it is going.

0

reply

(Original post by

c.i. The ball moves with some velocity which is changing. It has a vertical velocity component, and a horizontal velocity component. The horizontal one does not change at all and remains constant. Therefore, for the minimum speed, you want to identity what the minimum vertical component must be in that motion and use it in determining the magnitude of that velocity.

c.ii. Once you figure out WHEN precisely this minimum vertical velocity occurs (not in terms of time, but in terms of the motion) then it should be fairly obvious in what direction it is going.

**RDKGames**)c.i. The ball moves with some velocity which is changing. It has a vertical velocity component, and a horizontal velocity component. The horizontal one does not change at all and remains constant. Therefore, for the minimum speed, you want to identity what the minimum vertical component must be in that motion and use it in determining the magnitude of that velocity.

c.ii. Once you figure out WHEN precisely this minimum vertical velocity occurs (not in terms of time, but in terms of the motion) then it should be fairly obvious in what direction it is going.

0

reply

Report

#4

Hopefully you know that the velocity vector has a horizontal component and a vertical component.

One of those components is constant (because we neglect air resistance, bouyancy, etc) and the other changes throughout the trajectory at a constant rate.

Can you work out now what you need to consider & do to find min(velocity) ?

One of those components is constant (because we neglect air resistance, bouyancy, etc) and the other changes throughout the trajectory at a constant rate.

Can you work out now what you need to consider & do to find min(velocity) ?

0

reply

Report

#5

(Original post by

i know the vertical component is 20sin53 and the horizontal component is 20cos53 but how do i work out the minimum vertical component.

**Chez 01**)i know the vertical component is 20sin53 and the horizontal component is 20cos53 but how do i work out the minimum vertical component.

**vertical**speed occur?? What must it be?

0

reply

(Original post by

Think about the projectile moving. It must go up and then it must come down. When does the minimum

**RDKGames**)Think about the projectile moving. It must go up and then it must come down. When does the minimum

**vertical**speed occur?? What must it be?
0

reply

Report

#7

(Original post by

when its at the highest point? im not sure

**Chez 01**)when its at the highest point? im not sure

You don't even need to study Mechanics to know this, it's just intuitive.

0

reply

(Original post by

Of course! So what is the vertical speed at the highest point?

You don't even need to study Mechanics to know this, it's just intuitive.

**RDKGames**)Of course! So what is the vertical speed at the highest point?

You don't even need to study Mechanics to know this, it's just intuitive.

0

reply

Report

#9

(Original post by

zero?

**Chez 01**)zero?

So what's the overall speed since there is no vertical component?

0

reply

Report

#11

(Original post by

zero too, i think

**Chez 01**)zero too, i think

**know**isn't zero.

You have a velocity where there's a known horizontal vel, and vertical vel is 0... so the magnitude of this velocity is...?

0

reply

(Original post by

No, because we have the horizontal component which we

You have a velocity where there's a known horizontal vel, and vertical vel is 0... so the magnitude of this velocity is...?

**RDKGames**)No, because we have the horizontal component which we

**know**isn't zero.You have a velocity where there's a known horizontal vel, and vertical vel is 0... so the magnitude of this velocity is...?

0

reply

Report

#15

(Original post by

even thought velocity is 0 at that point?

**Chez 01**)even thought velocity is 0 at that point?

__velocity is zero at that point. Not the horizontal one! The horizontal one is 20cos53 throughout!__

**Vertical**
0

reply

(Original post by

(for the 100th time...)

**RDKGames**)(for the 100th time...)

__velocity is zero at that point. Not the horizontal one! The horizontal one is 20cos53 throughout!__**Vertical**
0

reply

X

Page 1 of 1

Go to first unread

Skip to page:

### Quick Reply

Back

to top

to top