Question 7 (1 point)
Unbalanced forces
a
cause the motion of an object to change.
b
can change an object's speed but not direction.
c
make an object move opposite the applied force.
d
maintain the constant motion of an object.
Question 8 (1 point)
Every few years, sailboats of different countries compete in a race for a trophy called the America's Cup. The boats sail over the same distance. What, besides the distance, is needed to find out the speed of each boat in the race?
a
the time it takes each boat to finish the race
b
the skill of the crew of each boat in the race
c
the speed of the wind during the race
d
the size of each boat in the race
Question 9 (1 point)
Which of the following is an example of an unbalanced force?
a
A person pushing a car up a hill
b
A car traveling at a constant speed on a flat road
c
A book sitting on a table
d
A ball rolling down a hill