Newtons Laws Investigate and describe applications of Newton’s laws
such as in vehicle restraints, sports activities, geological processes and
satellite orbits
____
7. In the picture below, a girl is sitting motionless on a swing. What is the net force on the
girl?
a.
b.
c.
d.
0 newtons
245 newtons upwards
490 newtons upwards
490 newtons downwards
Answers:
1 A Correct. Weight expresses the extent to which gravity pulls on an object.
B Incorrect. Newton's name is given only to the SI unit for force.
C Incorrect. Mass, not weight, expresses inertia.
D Incorrect. Mass and weight express different properties.
2 F Correct. The losses usually result from friction.
G Incorrect. A perfectly designed simple machine still suffers from lost energy.
H Incorrect. The mechanical advantages of simple machines far outweigh losses due to
friction.
J Incorrect. Any weight gains involved with simple machines are
overshadowed by mechanical advantage. ,
3 A Incorrect. Momentum is mass X velocity.
B Incorrect. Acceleration is change in velocity/time.
C Correct. Work is force X distance. Kg•m!s2 is an expression of force.
D Incorrect. Power is work/time.
4 F Incorrect. Inertia is the principle behind Newton's first law of motion.
G Incorrect. Inertia is the principle behind Newton's first law of motion.
H Incorrect. This resistance sums up Newton's first law.
J Correct. All of the statements apply to Newton's first law of motion.
5. A Incorrect . Air resistance is not included in acceleration calculations.
B Incorrect. Objects with greater weight experience a greater force due to gravity.
C Correct. An object with greater mass has greater inertia, which compensates for the
extra force upon it due to its greater weight.
D Incorrect. Mass is proportional to inertia.
6. F Incorrect. These forces are equal and opposite.
G Incorrect . These are equal and opposite forces.
H Incorrect. This is a classic equal and opposite force example.
J Correct. These forces are not equal and opposite, because the ball experiences gravity
long before it hits the ground.
Incorrect
7.
A