I had the same question
Karen is running forward at a speed of 9 m/s. She tosses her sweaty headband backward at a speed of 20 m/s.
2 answers:
Answer:
The speed of the headband, to the nearest whole number relative to a stationary observer watching Karen, is 11m/s
Explanation:
The velocity of the headband relative to the stationary observer is equal to the velocity of Karen relative to the stationary observer plus the velocity of the headband relative to Karen. Mathematically:
Where:
(it's negative because it mover backward)
: velocity of the headband relative to the stationary observer
Plugging these values
Speed is simply the magnitude of velocity or its absolute value, that is to say, 11m/s (positive)
You might be interested in
Answer:
The speed of player is given by
Explanation:
The time of flight for a projectile motion is given by
(i)
where t is the time of flight, v is the initial speed, and α is the angle.
Now the person must also reach the impact point of ball in the same time as above.
Now the total distance D the player needs to cover is basically R horizontal range of projectile minus the distance d, range R is given by,
Now the distance the player must cover is given by
D= R-d
D= - d
(ii)
Now the average speed of player is given by
(iii)
Replacing the values of D and T from eq. (i) and (ii) in eq. (iii).