A projectile is fired straight upward at 141 $\mathrm{m} / \mathrm{s}$ . How fast is it moving at the instant it reaches the top of its trajectory? Suppose that it were fired upward at $45^{\circ}$ instead. Then its horizontal component of velocity would be 100 $\mathrm{m} / \mathrm{s}$ . What would be the speed of the projectile at the top of its trajectory?