projectile motion help (1 Viewer)

[john-doe]

a cricketer can throw a ball 40m vertically upwards. what is his max throwing range on a flat cricket field?

 

[deswa1]

a cricketer can throw a ball 40m vertically upwards. what is his max throwing range on a flat cricket field?

Interesting question actually. I don't have time to work it out but the method I would do is this:

1. Find the velocity that the ball has when he throws (its vertically up-> use the displacement velocity thingos)
2. Note that max range occurs when the angle of throwing is 45 degrees
3. Calculate range using velocity from 1 and angle from 2

 

[john-doe]

Interesting question actually. I don't have time to work it out but the method I would do is this:

1. Find the velocity that the ball has when he throws (its vertically up-> use the displacement velocity thingos)
2. Note that max range occurs when the angle of throwing is 45 degrees
3. Calculate range using velocity from 1 and angle from 2

the answer is 80 but i keep getting 160...i must be going somewhere wrong but cant find it!

 

[Sy123]

We can derive that the range of a ball is:



The maximum range occurs at 45 degrees (can be shown mathematically)



We are going to assume g=10.

Now to calculate V, we know that he can throw vertically upwards a ball for 40m, lets find the vertical motion of this bal:



The equation above is found by intergrating and finding +C which is V in this case (since it is vertical)
Now at

Maximum height which is 40m is achieved.

So finding the time t when the ball is at maximum height (when thrown vertically upwards)



Sub this into our y equation and sub in y=40





So we found our velocity, plug it into our original x equation:

 

[john-doe]

We can derive that the range of a ball is:



The maximum range occurs at 45 degrees (can be shown mathematically)



We are going to assume g=10.

Now to calculate V, we know that he can throw vertically upwards a ball for 40m, lets find the vertical motion of this bal:



The equation above is found by intergrating and finding +C which is V in this case (since it is vertical)
Now at

Maximum height which is 40m is achieved.

So finding the time t when the ball is at maximum height (when thrown vertically upwards)



Sub this into our y equation and sub in y=40





So we found our velocity, plug it into our original x equation:

thanks...instead of y(dot)= -gt + V, i used y(dot)= -gt + Vsin(theta)....