What's the correct answer and why?
1. If action and reaction forces are always equal and opposite then why do objects move at all?
a) one object has more mass than the other
b) the forces act on different objects
c) the reaction forces take over since the action forces acted first
d) the reaction force is slower to react because of inertia
e) the action and reaction forces are not exactly equal
2. True or false: Work done is zero when uniform motion exists in the absence of a force.
3. A weight lifter lowers a barbell at constant speed. Down is assigned as positive. In doing so, the weight lifter:
a) does positive work on the barbell
b) allows gravity to do negative work on the barbell
c) does not do any work on the barbell
d) does negative work on the barbell
e) allows the kinetic energy of the barbell to increase.
4. True or false: The shimmering effect noticed above a hot fire is due to total internal reflection between the layers of air at different temperatures above the flames.
5. True or false: A circuit has a single load connected to a battery. If a second load is connected in parallel to the first load, the equivalent resistance of the circuit must decrease.
Thanks.
1. If action and reaction forces are always equal and opposite then why do objects move at all?
a) one object has more mass than the other
b) the forces act on different objects
c) the reaction forces take over since the action forces acted first
d) the reaction force is slower to react because of inertia
e) the action and reaction forces are not exactly equal
2. True or false: Work done is zero when uniform motion exists in the absence of a force.
3. A weight lifter lowers a barbell at constant speed. Down is assigned as positive. In doing so, the weight lifter:
a) does positive work on the barbell
b) allows gravity to do negative work on the barbell
c) does not do any work on the barbell
d) does negative work on the barbell
e) allows the kinetic energy of the barbell to increase.
4. True or false: The shimmering effect noticed above a hot fire is due to total internal reflection between the layers of air at different temperatures above the flames.
5. True or false: A circuit has a single load connected to a battery. If a second load is connected in parallel to the first load, the equivalent resistance of the circuit must decrease.
Thanks.