Question

Snowballs are thrown with a speed of 13 m/s from a roof 7.0 m above the ground. Snowball A is thrown straight downward; snowball B is thrown in a direction 25o above the horizontal. When the snowballs land, is the speed of A greater than, less than, or the same speed of B? Verify your answer by calculation of the landing speed of both

Answer 1

Answer:

Speed of both the ball will be same

Explanation:

For snow ball A

Initial velocity u = 13 m/sec

Acceleration due gravity $g=9.8m/sec^2$

According to third law of motion

$v^2=u^2+2gh$

So $v^2=13^2+2\times 9.8\times 7$

v = 17.5 m/sec, here v is final velocity

For snow ball B

Initial velocity v = 13 m/sec

Angle with horizontal = 25°

Horizontal component of velocity $u_x=ucos\Theta =13\times cos25^{\circ}=11.782m/sec$

Vertical component of velocity

$v_y^2=u_y^2+2gh$

$v_y^2=(usin\Theta )^2+2gh$

$v_y^2=(13sin25^{\circ})^2+2\times 9.8\times 7=167.3844$

$v_y=12.93m/sec$

So resultant velocity of ball B $V=\sqrt{v_x^2+v_y^2}=\sqrt{11.78^2+12.93^2}=17.5m/sec$

So speed of both the ball will be same