Physics - Mechanics (6)

Question 1

Newton’s 1st law

Answer 1

An object will only change its motion if a force acts upon it

Question 2

What does projectile motion mean?

Answer 2

No air resistance.
The only force acting is gravity.
Gravity is uniform and downward

Question 3

Newton’s 2nd law

Answer 3

F=ma. It will accelerate in proportion to the mass.

Question 4

Newton’s 3rd law

Answer 4

Forces exist in equal and opposite pairs

Question 5

What if f=kx?

Answer 5

F = Force
K = Spring constant, or stiffness (N/m)
x = Extension

Question 6

Elastic and plastic deformation

Answer 6

Elastic - Material returns to original shape
Plastic - The material is perminantley destroyed

Question 7

Why does increased time in momentum result in less force?

Answer 7

Decreasing the time for the collision while the momentum change is the same, increases the force, so it has a larger force acting upon it. It suffers more damage.

Question 8

Centripetal motion where the thing falls out of this motion.

Answer 8

1. It experieces a centripetal force provided by the friction.
2. The speed increases, reaching a point where the cent force needed exceeds what the friction can provide.
3. It slides off, it no longer experiences the centripetal force, moves in the direction of its tangent.

Question 9

We have Vh, what is Vv?

Answer 9

Using 1/2 the time gives us the max height, where vvf= 0. Vf = vi+at.
To find the real one & angle, use pythagerus & trig

Question 10

What does lower gravity mean for projectile motion?

Answer 10

Less gravity means that the object is pulled back to earth slower. This increases the time in the air, which increases the distance it travels horizontally, as the velocity is constant

Question 11

What are the forces acting upon an object in projectile motion?

Answer 11

F=mg. Mass x gravity

Question 12

Changes to make to springs to make the force less

Answer 12

1. Decrease k. This increases the time as springs compress more. The force decreases, p=ft
2. Add more springs to distribute the force

Question 13

Torque. Someone moving closer to side B.

Answer 13

A feels a decrease in force. As it moves closer to B, the anticlockwise torque decreases, causing a decrease in force on A.

Question 14

What happens to momentum if we’re talking vertically?

Answer 14

Momentum isn’t conserved, as an external force (gravity) is acting upon it.