IB PHYSICSGOHS
TOPIC 2.1 Kinematic Equations: suvat equations
1. A drag racer starts her car from rest and accelerates at 10.0 m/s2 for the entire distance of 400 m (¼ mile). (a) How long did it take the race car to travel this distance? (b) What is the speed of the race car at the end of the run?
2. A jet plane lands with a speed of 100 m/s and can accelerate at a maximum rate of –5.00 m/s2 as it comes to rest. (a) From the instant the plane touches the runway, what is the minimum time needed before it can come to rest? (b) Can this plane land on a small tropical island airport where the runway is 0.800 km long?
3. A driver in a car traveling at a speed of 60 mi/h sees a deer 100 m away on the road. Calculate the minimum constant acceleration that is necessary for the car to stop without hitting the deer (assuming that the deer does not move in the meantime).
4. A record of travel along a straight path is as follows.
Start from rest with constant acceleration of 2.77 m/s2 for 15.0 s
Constant velocity for the next 2.05 min
Constant negative acceleration –9.47 m/s2 for 4.39 s
What was the total displacement for the complete trip?
What were the average speeds for legs 1, 2, and 3 of the trip as well as for the complete trip?
5. A car accelerates uniformly from rest to a speed of 40.0 mi/h in 12.0 s. (a) Find the distance the car travels during this time and (b) the constant acceleration of the car.
6. A car starts from rest and travels for 5.0 s with a uniform acceleration of + 1.5 m/s2. The driver then applies the brakes, causing a uniform acceleration of -2.0 m/s2. If the brakes are applied for 3.0 s, (a) how fast is the car going at the end of the braking period, and (b) how far has it gone?
ANSWERS
1. (a)Using with gives , yielding t=.
(b)From , with , we find .
2. (a)The time required to stop is .
(b)The minimum distance needed to stop the plane is
.
Thus, the plane cannot stop in 0.8 km.
3.Using , with and , yields
.
4. The velocity at the end of the first interval is
.
This is also the constant velocity during the second interval and the initial velocity for the third interval.
(a)From , the total displacement is
or
(b),
,
, and the average velocity for the
total trip is
5.
(a)To find the distance traveled, we use
.
(b)The acceleration is .
6. At the end of the acceleration period, the velocity is
.
This is also the initial velocity for the braking period.
(a)After braking, .
(b)The total distance traveled is
.