Problem 1: A light-rail commuter train accelerates at a rate of 1.1 m/s2.
Part (a) How long does it take to reach its top speed of 75 km/h, in seconds, starting from rest?
Numeric : A numeric value is expected and not an expression.
t = __________________________________________
Part (b) The same train ordinarily brakes at a rate of 1.6 m/s2. How long does it take to come to a stop, in seconds, from its top speed?
Numeric : A numeric value is expected and not an expression.
tb = __________________________________________
Part (c) In emergencies the train can slow more rapidly, coming to rest from 75 km/h in 8.15 s. What is the magnitude of the acceleration during emergency braking, in meters per square second?
Numeric : A numeric value is expected and not an expression.
ae = __________________________________________
Problem 2: A car travels a distance d = 26.5 m in the positive x-direction in a time of t1 = 18 s. The car immediately brakes and comes to rest in t2 = 7 s.
Randomized Variables
d = 26.5 m
t1 = 18 s
t2 = 7 s
Part (a) What was the car’s average velocity in the horizontal direction, in meters per second, during t1?
Numeric : A numeric value is expected and not an expression.
vavg = __________________________________________
Part (b) What was the acceleration, in meters per second squared, during time interval t1, assuming the car started from rest and moved with a constant acceleration?
Numeric : A numeric value is expected and not an expression.
a = __________________________________________
Part (c) What was the car’s instantaneous velocity in the horizontal direction, in meters per second, when it began braking?
Numeric : A numeric value is expected and not an expression.
v(t1) = __________________________________________
Part (d) Using the result from part (c), what was the car’s horizontal component of acceleration, in meters per second squared, during the braking period?
Numeric : A numeric value is expected and not an expression.
ab = __________________________________________
Problem 3: A basketball referee tosses the ball straight up for the starting tipoff.
At what speed must a basketball player leave the ground to rise 1.45 m above the floor in an attempt to get the ball?
Numeric : A numeric value is expected and not an expression.
v0 = __________________________________________
Problem 4: A rescue helicopter is hovering over a person whose boat has sunk. One of the rescuers throws a life preserver straight down to the person with an initial speed of 1.3 m/s and observes that it takes 1.95 s to reach the water.
How high above the water was the preserver released? Note that the downdraft of the helicopter reduces the effect of air resistance on the falling life preserver, so that an acceleration equal to that due to gravity is reasonable.
Numeric : A numeric value is expected and not an expression.
y0 = __________________________________________
Problem 5: The position of a moving object was measured at various times and the results are shown in the table and graphed in the figure.
Take the slope of the curve to determine the velocity, in meters per second, at time t = 30.0 s.
Numeric : A numeric value is expected and not an expression.
v = __________________________________________