1. A child, whose weight is 150 N, lifts a pumpkin from the ground with a force of 50 N. The force the pumpkin exerts on the child is:
1. More than 50 N
2. 50 N
3. Greater than zero but less than 50 N
4. Zero
2. A car rounds a curve while maintaining constant speed. The correct statement is:
1. A net force acts upon the car
2. The velocity of the car is zero
3. No net force acts on the car
4. The velocity of the car is constant
5. The acceleration of the car is zero
3. A body is suspended from a spring hanging vertically. The body is then pulled downward so the spring stretches. Consider the change in the elastic potential energy (EPE) of the spring and the change in gravitational potential energy (GPE) as the body are pulled down.
1. The GPE and the EPE decrease
2. The GPE increases along with the EPE
3. The GPE decreases while the EPE increases
4. The GPE decreases but the EPE is unchanged
5. The EPE increases but the GPE is unchanged
4. Can the gravitational force of Earth do positive or negative work on a geosynchronous communication satellite once it is on its circular orbit?
1. Yes, because its speed is constant
2. Yes, because centripetal forces always do positive work
3. No, because the satellite has zero acceleration
4. No, because the force is always perpendicular to the orbital path
5. A brick slides across a horizontal rough surface and eventually comes to a stop. What happened to the kinetic energy of the brick?
1. It was converted to a potential energy of friction
2. It was converted to other energy forms, mostly heat
3. It was simply destroyed in the process of stopping
4. Nothing; it is still in the brick but is now called potential energy
EXPLAIN WHY IT IS THAT ANSWER!