CH. 3 HW Part A

What is the average speed in kilometers per hour of a horse that gallops a distance of 15 km in a time of 30 min? a) 30 km/h b) 15 km/h c) 2 km/h d) 0.5 km/h

a) 30 km/h

Jogging Jake runs at 4 m/s along a train flatcar that moves at 10 m/s in the opposite direction. Jake's speed relative to the ground is a) 6 m/s b) 10 m/s c) 14 m/s d) none of the above

a) 6 m/s

What kind of speed is registered by an automobile speedometer? a) instantaneous speed b) average speed c) minimum speed d) maximum speed

a) instantaneous speed

If a car is moving at 90 km/h and it rounds a corner, also at 90 km/h, does it maintain a constant speed? A constant velocity? a) it maintains a constant speed, but does not maintain a constant velocity b) it maintains a constant velocity, but not a constant speed c) it maintains a constant speed and a constant velocity d) it does not maintain a constant speed or a constant velocity

a) it maintains a constant speed, but does not maintain a constant velocity

The average speed of a horse that gallops 10 kilometers in 30 minutes is a) 40 km/h b) 15 km/h c) 20 km/h d) 30 km/h

b) 20 km/h

Select the correct equations that show that if the river flows at 4 m/s, the speed of the boat relative to the riverbank is 5 m/s. a) v=v2/1 + v2/2= (3m/s)^2 + (4m/s)^2= 5m/s b) v=√v2/1 + v2/2= √(3m/s)^2 + (4m/s)^2 = 5m/s c) v= √v1 + v2 = √3m/s + 4m/s = 5m/s d) v=v1 + v2 = 3m/s +4m/s = 5m/s

b) v=√v2/1 + v2/2= √(3m/s)^2 + (4m/s)^2 = 5m/s

What is the main difference between speed and velocity? a) velocity is constant, but speed always changes b) velocity includes a direction, but speed does not c) speed is constant, but velocity always changes d) speed includes a direction, but velocity does not

b) velocity includes a direction, but speed does not

If a car moves with a constant velocity, does it also move with a constant speed? a) yes, because velocity and speed are identical b) no, because velocity is always greater than speed c) yes, because constant velocity requires constant speed in the same direction d) no, because the direction of the velocity might change to counteract the change in speed

c)yes, because constant velocity requires constant speed in the same direction

What two units of measurement are necessary for describing speed? a) average speed and distance b) distance and length c) average speed and time d) distance and time

d) distance and time

A hamster has an acceleration of 2 m/s^2. Select the correct equations that show that the hamster travels a distance of 49 m in 7 s. a) s=t^2/(2a)=(7s)^2/(2*(2m/s^2))= 49 m b) s=a*t/2=(2m/s^2)*(7s)/2= 49 m c) s=a^2*t/2=(2m/s^2)^2*(7s)/2= 49 m d) s=a*t^2/2=2m/s^2*(7s)^2/2= 49 m

d) s=a*t^2/2=2m/s^2*(7s)^2/2= 49 m