Does A Car Headrest Help To Guard Against Whiplash In A Rear-End Collision?
14. In terms of Newton’s fist law, how does a car headrest help to guard against whiplash in a rear end collision?
In a rear-end collision, your body moves forward with the car, your head is at rest and tends to stay at rest. Relative to your body, which means it is jerking back. The headrest brings your head along with the rest of the body.
18. Each bone in the chain of bones forming your spine is separated from its neighbors by disks of elastic tissue. What happens, then, when you jump heavily onto your feet from an elevated position? Can you think of a reason why you are a little taller in the morning than at night?
Each of the elastic tissue tends to compress to each other because of newton’s first law.
23. Can an object be in …show more content…
Starting from rest, one car accelerates to a speed of 50km/h, and another car accelerates to a speed of 60km/h. Can you say which car underwent the greater acceleration? Why or why not?
We cannot tell which car underwent the greater acceleration without knowing the time.
30. Someone standing at the edge of a cliff throws a ball nearly straight up at a certain speed and another ball nearly straight up at a certain speed and another ball nearly straight down with the same initial speed. If air resistance is negligible, which ball will have the greater speed when it strikes the ground below?
Both balls strike the ground with the same speed. The ball thrown upwards has the same initial speed as the one thrown downwards.
35. Consider a vertically launched projectile when air drag is negligible. When is the acceleration due to gravity greater? When ascending, at the top, or when descending? Defend your answer.
The acceleration due to gravity remains a constant g at all points along its path as long as no other forces like air drag act on the projectile.
36. Extend tables 3.2 and 3.3 to include times of fall of 6 to 10 s assuming no air resistance time of fall (seconds)
Velocity acquired (Meters/ second) 0
0
1
In a rear-end collision, your body moves forward with the car, your head is at rest and tends to stay at rest. Relative to your body, which means it is jerking back. The headrest brings your head along with the rest of the body.
18. Each bone in the chain of bones forming your spine is separated from its neighbors by disks of elastic tissue. What happens, then, when you jump heavily onto your feet from an elevated position? Can you think of a reason why you are a little taller in the morning than at night?
Each of the elastic tissue tends to compress to each other because of newton’s first law.
23. Can an object be in …show more content…
Starting from rest, one car accelerates to a speed of 50km/h, and another car accelerates to a speed of 60km/h. Can you say which car underwent the greater acceleration? Why or why not?
We cannot tell which car underwent the greater acceleration without knowing the time.
30. Someone standing at the edge of a cliff throws a ball nearly straight up at a certain speed and another ball nearly straight up at a certain speed and another ball nearly straight down with the same initial speed. If air resistance is negligible, which ball will have the greater speed when it strikes the ground below?
Both balls strike the ground with the same speed. The ball thrown upwards has the same initial speed as the one thrown downwards.
35. Consider a vertically launched projectile when air drag is negligible. When is the acceleration due to gravity greater? When ascending, at the top, or when descending? Defend your answer.
The acceleration due to gravity remains a constant g at all points along its path as long as no other forces like air drag act on the projectile.
36. Extend tables 3.2 and 3.3 to include times of fall of 6 to 10 s assuming no air resistance time of fall (seconds)
Velocity acquired (Meters/ second) 0
0
1