Physics/motion in straight line
QUESTION: A bus is moving with a speed of 10 m/s on a straight road . A scooterist wishes to overtake the bus in 100 s. If the bus is at a distance of 1 km from the scooterist, with what speed should scooterist chase the bus?
ANSWER: Make the final positions of both the bus and the scooter the same.
For the bus the position is Dbus=10m/s*100s
For the scooter the position is Dscooter=V*100s-1000 (Since the scooter starts 1000m behind the bus.)
Make these equal:
solving for the velocity:
---------- FOLLOW-UP ----------
QUESTION: an object thrown vertically up from the ground passes the height 5 m twice in an interval of 10 s. what is its time of flight?[option:1)root 28 s 2)root 86 s 3)root 104 s 4)root 72 s ]
First calculate the velocity of the object as it passes the 5m mark:
do=5m, df=5m, vo=?, vf=?, a=-9.8m/s^2, t=10s
Solving for the velocity as the object passes the 5m mark:
Now that we know the velocity as the object passes the 5m mark we can now solve for velocity with which the object leaves the ground using:
Solving for Vo:
So the total flight time will be:
Do=0m, Df=0m, Vo=50m/s, Vf=-50m/s, a=-9.8m/s^2, t=?
Which is the square root of 104, so c) is the correct answer.