1. Parabola
The path taken by a projectil is known as parabola, and it consists of two independent motions:
- along the horizontal direction, it is a uniform motion with constant speed
- along the vertical direction, it is an accelerated motion with constant acceleration, g=9.8 m/s^2 downward
2. A person sitting in a chair, not moving
This is NOT a motion of a projectile. In fact, the person is not moving at all, so this is not a motion.
3. 490 meters
The supplies will move of uniform accelerated motion, with constant acceleration g=9.8 m/s^2, so the distance they cover is given by
[tex]S=\frac{1}{2}gt^2=\frac{1}{2}(9.8 m/s^2)(10 s)^2 =490 m[/tex]
4. 65 m/s
The horizontal motion of the supplies is a uniform motion, with constant speed equal to the ratio between the horizontal distance covered and the time taken:
[tex]v=\frac{d}{t}=\frac{650 m}{10 s}=65 m/s[/tex]
5. True
As explaned in exercise 1), a projectile has two independent motions: one along the horizontal direction and one along the vertical direction. Therefore, it also has a horizontal component of the velocity (which is constant) and a vertical component of the velocity (which changes because there is an acceleration acting along this direction)
6. False
As stated in exercise 1) and 2) the trajectory of a projectile is a parabola, not an ellipse.
7. The vertical component always equals the horizontal component
This statement is not true: as we said, the horizontal component of the velocity is constant, while the vertical component constantly changes, so they cannot be always equal (in fact, they will be equal only at some precise instant of the motion)
8. constant
As stated before, there is no force acting along the horizontal direction of the projectile's motion, so the horizontal acceleration is zero, and this means that the horizontal velocity is constant.
9. Vertical velocity decreases.
When the projectile is moving upward, its vertical velocity decreases, because the acceleration (which acts downward) acts in the opposite direction of the velocity. More specifically, the vertical velocity is given by
[tex]v_y(t)=v_{0y}-gt[/tex]
where v0y is the initial vertical velocity of the projectile, t is the time and g=9.8 m/s^2.
10. Vertical velocity increases.
When the projectile is moving downward, its vertical velocity increases, because the acceleration (which acts downward) this time is acting in the same direction of the velocity
The path a projectile takes is called Trajectory
In terms of projectile motion, trajectory is the curved path that an object follows when it travels in space. It has two components x and y. X component shows the range while y component shows the height of the projectile.
The odd choice out of these options is A person sitting in a chair, not moving
For a projectile motion, movement is necessary in a curved path. Since the person sitting in a chair is not moving and he is in rest so he cannot be considered as moving.
The distance will be 490 meters
According to second equation of motion
S= vit + ½ gt²
Putting the values
S = 0 + ½ (9.8) (10)
S = 490 meters
The speed will be 65m/s
As we know that
Speed = Distance / Time
So putting the values
Speed = 650 / 10
Speed = 65 m/s
The given statement is true
A projectile motion is composed up of two components. X component is responsible for showing the range and Y component is responsible for the height of the projectile.
The given statement is false
The shape of projectile graph is a parabola, not an ellipse. The equation of a projectile gives us two values at two different points. Since it is a quadratic equation so that is why this type of motion gives parabola and not an ellipse.
The false statement is vertical component is always equals to horizontal component.
The horizontal component of a projectile is X and it is constant which means no force is acting on it whereas y component has a force of gravity so both of these components can never be the same.
During the course of trajectory, the horizontal component of the velocity is constant.
The horizontal component of trajectory is the X component. This component does not have any force upon it except the force of friction of earth and object. The force of friction is also acting in x axis that is why we can say that during the course of trajectory, the horizontal component of the velocity is constant.
In the simulation above, as the projectile travels upward, its vertical velocity decreases
Whenever an object moves against the force of gravity, it’s acceleration and velocity decreases because the gravitational pull tends the object to stay it on earth surface.
In the simulation above, as the projectile travels downward, the vertical velocity increases
As the body comes towards the earth the gravitational acceleration increases with the rate of 9.8m/s². This acceleration is taken as positive and when the projectile hits the ground it is in its maximum speed.
