Question

A placekicker kicks a football upward at an angle of 30 and a speed of 5.0 m/s at what other angle will he have to kick a second ball with the same speed to reach the same distance downrange ignore air resistance

60

90

45

15

Answer 1

Answer:
`60^(\circ)`

Step-by-step explanation:

Given

speed of ball
`u=5 m/s`

launch angle
`\theta =30^(\circ)`

Range of a Projectile
`R=(u^2\sin 2\theta )/(g)`

Range will be common for two angles i.e.
`\theta [tex] and [tex]90-\theta`

for
`\theta R=(5^2\sin 2\cdot 30)/(g)`

`R=2.209 m`

For
`90-\theta`

`90-30=60^(\circ)`

`R=(5^2\sin 2\cdot 60)/(g)`

`R=2.209 m`

Answer 2

The other angle is 60°

(a) is correct option.

Step-by-step explanation:

Given that,

Angle = 30

Speed = 5.0 m/s

We need to calculate the range

Using formula of range

`R=(v^2\sin(2\theta))/(g)`...(I)

The range for other angle is

`R=(v^2\sin(2(\alpha-\theta)))/(g)`...(II)

Here, distance and speed are same

From equation (I) and (II)

`(v^2\sin(2\theta))/(g)=(v^2\sin(2(\alpha-\theta)))/(g)`

`\sin(2\theta)=\sin(2(\alpha-\theta))`

Put the value into the formula

`\sin(2*30)=\sin(2*(\alpha-\theta))`

`\sin60=\sin2(\alpha-30)`

`60=2\alpha-60`

`\alpha=(60+60)/(2)`

`\alpha=60^(\circ)`

Hence, The other angle is 60°.