Complete Question
An airplane takes off a runway at a constant speed of 49 m/s at constant angle 30 to the horizontal.How high (in meters ) is the airplane above the ground 13 seconds after takeoff?
Answer:
The height is 
Explanation:
From the question we are told that
The speed at which the plane takes off is 
The angle at which it takes off is 
The time taken is 
The vertical distance traveled is mathematically represented as

Substituting values


Hello
The bullet is moving by uniformly accelerated motion.
The initial velocity is

, the final velocity is

, and the total time of the motion is

, so the acceleration is given by
where the negative sign means that is a deceleration.
Therefore we can calculate the total distance covered by the bullet in its motion using

So, the bullet penetrates the sandbag 1.8 meters.
Answer:
B. The truck and mosquito exert the same size force on each other.
Explanation:
Newton's third law (law of action-reaction) states that
"When an object A exerts a force (action) on an object B, then object B exerts an equal and opposite force (reaction) on object A"
In this case, we can call
object A = the truck
object B = the mosquito
Thereforce according to Newton's third law, the force exerted by the truck on the mosquito is equal in magnitude to the force exerted by the mosquito on the truck (and in opposite direction).
The reason for which the mosquito will experience much more damage is the fact that the mosquito's mass is much smaller than the truck's mass, and since the acceleration is inversely proportional to the mass:

the mosquito will experience a much larger deceleration than the truck, therefore much more damage.
<span>c. atoms are always in motion..............</span>
Missing question: "What is the spring's constant?"
Solution:
The object of mass m=6.89 kg exerts a force on the spring equal to its weight:

When the object is attached to the spring, the displacement of the spring with respect to its equilibrium position is

And by using Hook's law, we can find the constant of the spring: