A projectile is fired at an angle of 55.0° above the horizontal with an initial speed of 35.0 m/s.
-How long does it take the projectile to reach the highest point in its trajectory?
A)1.5 s
B)2.4 s
C)4.0 s
D)6.2 s
E)9.8 s

Question

Quizplus · Accepted Answer

The time it takes for the projectile to reach the highest point in its trajectory can be calculated using the formula: 
time = (vertical initial velocity) / (gravitational acceleration) 
At the highest point, the vertical initial velocity is zero, so we can use: 
time = (vertical final velocity) / (gravitational acceleration) 
The vertical final velocity at the highest point can be calculated using: 
vertical final velocity = (initial velocity) * sin(angle) 
where angle is the angle of the initial velocity vector with the horizontal. 
Using the given values, we get: 
vertical final velocity = (35.0 m/s) * sin(55.0°) ≈ 28.4 m/s 
time = (28.4 m/s) / (9.81 m/s^2) ≈ 2.89 s 
Therefore, the answer is B) 2.4 s, which is the closest choice to our calculation.

A Projectile Is Fired at an Angle of 55