PHYSICS - Misconceptual Questions

Four students use different instruments to measure the length of the same pen. Which measurement implies the greatest precision? A. 160.0 mm. B. 16.0 cm. C. 0.160 m. D. 0.00016 km. E. Need more information.

A. 160.0 mm.

You drop a rock off a bridge. When the rock has fallen 4 m, you drop a second rock. As the two rocks continue to fall, what happens to their velocities? A. Both increase at the same rate. B. The velocity of the first rock increases faster than the velocity of the second. C. The velocity of the second rock increases faster than the velocity of the first. D. Both velocities stay constant.

A. Both increase at the same rate.

A truck is traveling horizontally to the right. When the truck starts to slow down, the crate on the (frictionless) truck bed starts to slide. In what direction could the net force be on the crate? A. No direction. The net force is zero. B. Straight down (because of gravity). C. Straight up (the normal force). D. Horizontal and to the right. E. Horizontal and to the left.

A. No direction. The net force is zero.

A bullet fired from a rifle begins to fall A. as soon as it leaves the barrel. B. after air friction reduces its speed. C. not at all if air resistance is ignored.

A. as soon as it leaves the barrel.

A car travels 10 m/s east. Another car travels 10 m/s north. The relative speed of the first car with respect to the second is A. less than 20 m/s. B. exactly 20 m/s. C. more than 20 m/s.

A. less than 20 m/s.

To pull an old stump out of the ground, you and a friend tie two ropes to the stump. You pull on it with a force of 500 N to the north while your friend pulls with a force of 450 N to the northwest. The total force from the two ropes is A. less than 950 N. B. exactly 950 N. C. more than 950 N.

A. less than 950 N.

The magnitude of a component of a vector must be A. less than or equal to the magnitude of the vector. B. equal to the magnitude of the vector. C. greater than or equal to the magnitude of the vector. D. less than, equal to, or greater than the magnitude of the vector.

A. less than or equal to the magnitude of the vector.

You are in the middle of a large field. You walk in a straight line for 100 m, then turn left and walk 100 m more in a straight line before stopping. When you stop, you are 100 m from your starting point. By how many degress did you turn? A. 90°. B. 120°. C. 30°. D. 180°. E. This is impossible. You cannot walk 200 m and be only 100 m away from where you started.

B. 120°.

The number 0.0078 has how many significant figures? A. 1. B. 2. C. 3. D. 4.

B. 2

How many significant figures 1.362 + 25.2 does have? A. 2. B. 3. C. 4. D. 5.

B. 3

A golf ball is hit with a golf club. While the ball flies through the air, which forces act on the ball? Neglect air resistance. A. The force of the golf club acting on the ball. B. The force of gravity acting on the ball. C. The force of the ball moving forward through the air. D. All of the above. E. Both (a) and (c).

B. The force of gravity acting on the ball.

Two satellites orbit the Earth in circular orbits of the same radius. One satellite is twice as massive as the other. Which statement is true about the speeds of these satellites? A. The heavier satellite moves twice as fast as the lighter one. B. The two satellites have the same speed. C. The lighter satellite moves twice as fast as the heavier one. D. The ratio of their speeds depends on the orbital radius.

B. The two satellites have the same speed.

Accuracy represents A. repeatability of a measurement, using a given instrument. B. how close a measurement is to the true value. C. an ideal number of measurements to make. D. how poorly an instrument is operating.

B. how close a measurement is to the true value.

You are adding vectors of length 20 and 40 units. Which of the following choices is a possible resultant magnitude? A. 0. B. 18. C. 37. D. 64. E. 100.

C. 37.

You are riding in an enclosed train car moving at 90 km/h. If you throw a baseball straight up, where will the baseball land? A. In front of you. B. Behind you. C. In your hand. D. Can't decide from the given information.

C. In your hand.

A space shuttle in orbit around the Earth carries its payload with its mechanical arm. Suddenly, the arm malfunctions and releases the payload. What will happen to the payload? A. It will fall straight down and hit the Earth. B. It will follow a curved path and eventually hit the Earth. C. It will remain in the same orbit with the shuttle. D. It will drift out into deep space.

C. It will remain in the same orbit with the shuttle.

You drive 4 km at 30 km/h and then another 4 km at 50 km/h. What is your average speed for the whole 8-km trip? A. More than 40 km/h. B. Equal to 40 km/h. C. Less than 40 km/h. D. Not enough information.

C. Less than 40 km/h. **use v=d/t

A ball is dropped from the top of a tall building. At the same instant, a second ball is thrown upward from the ground level. When the two balls pass one another, one on the way up, the other on the way down, compare the magnitudes of their acceleration: A. The acceleration of the dropped ball is greater. B. The acceleration of the ball thrown upward is greater. C. The acceleration of both balls is the same. D. The acceleration changes during the motion, so you cannot predict the exact value when the two balls pass each other. E. The accelerations are in opposite directions.

C. The acceleration of both balls is the same.

What causes the boat in Fig. 4-41 to move forward? A. The force the man exerts on the paddle. B. The force the paddle exerts on the water. C. The force the water exerts on the paddle. D. The motion of the water itself.

C. The force the water exerts on the paddle.

A person stands on a scale in an elevator. His apparent weight will be the greatest when the elevator A. is standing still. B. is moving upward at constant velocity. C. is accelerating upward. D. is moving downward at constant velocity. E. is accelerating downward.

C. is accelerating upward.

When a skier skis down a hill, the normal force exerted on the skier by the hill is A. equal to the weight of the skier. B. greater than the weight of the skier. C. less than the weight of the skier.

C. less than the weight of the skier.

In the International Space Station which orbits Earth, astronauts experience apparent weightlessness because A.the station is so far away from the center of the Earth. B. the station is kept in orbit by a centrifugal force that counteracts the Earth's gravity. C. the astronauts and the station are in free fall towards the center of the Earth. D. there is no gravity in space. E. the station's high speed nullifies the effects of gravity.

C. the astronauts and the station are in free fall towards the center of the Earth.

A baseball is hit high and far. Which of the following statements is true? At the highest point, A. the magnitude of the acceleration is zero. B. the magnitude of the velocity is zero. C. the magnitude of the velocity is the slowest. D. more than one of the above is true. E. none of the above are true.

C. the magnitude of the velocity is the slowest.

A ball is thrown straight up. What are the velocity and acceleration of the ball at the highest point in its path? a. v=0, a=0. b. v=0, a=9.8 m/s^2 up. c. v=0, a=9.8 m/s^2 down. d. v=9.8 m/s up, a=0 . e. v=9.8 m/s down, a=0.

C. v=0, a=9.8 m/s^2 down.

In which of the following cases does a car have a negative velocity and a positive acceleration? A car that is traveling in the A. -x direction at a constant 20 m/s. B. -x direction increasing in speed. C. +x direction increasing in speed. D. -x direction decreasing in speed. E. +x direction decreasing in speed.

D. -x direction decreasing in speed.

*[L^2] represents the dimensions for which of the following? A. cm^2 B. square feet C. m^2 D. All of the above

D. All of the above

A car drives at steady speed around a perfectly circular track. A. The car's acceleration is zero. B. The net force on the car is zero. C. Both the acceleration and net force on the car point outward. D. Both the acceleration and net force on the car point inward. E. If there is no friction, the acceleration is outward.

D. Both the acceleration and net force on the car point inward.

At time t = 0 an object is traveling to the right along the +x axis at a speed of 10.0 m/s with acceleration -2.0 m/s^2 . Which statement is true? A. The object will slow down, eventually coming to a complete stop. B. The object cannot have a negative acceleration and be moving to the right. C. The object will continue to move to the right, slowing down but never coming to a complete stop. D. The object will slow down, momentarily stopping, then pick up speed moving to the left.

D. The object will slow down, momentarily stopping, then pick up speed moving to the left.

A bear sling, Fig. 4-40, is used in some national parks for placing backpackers' food out of the reach of bears. As the backpacker raises the pack by pulling down on the rope, the force F needed: A. decreases as the pack rises until the rope is straight across. B. doesn't change. C. increases until the rope is straight. D. increases but the rope always sags where the pack hangs.

D. increases but the rope always sags where the pack hangs.

To convert from ft^2 to yd^2 , you should A. multiply by 3. B. multiply by 1/3. C. multiply by 9. D. multiply by 1/9. E. multiply by 6. F. multiply by 1/6.

D. multiply by 1/9.

A student's weight displayed on a digital scale is 117.2 lb. This would suggest her weight is A. within 1% of 117.2 lb. B. exactly 117.2 lb. C. somewhere between 117.18 and 117.22 lb. D. somewhere between 117.0 and 117.4 lb.

D. somewhere between 117.0 and 117.4 lb.

Matt, in the foreground of Fig. 4-39, is able to move the large truck because A. he is stronger than the truck. B. he is heavier in some respects than the truck. C. he exerts a greater force on the truck than the truck exerts back on him. D. the ground exerts a greater friction force on Matt than it does on the truck. E. the truck offers no resistance because its brakes are off.

D. the ground exerts a greater friction force on Matt than it does on the truck.

Which of the following point towards the center of the circle in uniform circular motion? A. Acceleration. B. Velocity, acceleration, net force. C. Velocity, acceleration. D. Velocity, net force. E. Acceleration, net force.

E. Acceleration, net force.

Which is not true about an order-of-magnitude estimation? A. It gives you a rough idea of the answer. B. It can be done by keeping only one significant figure. C. It can be used to check if an exact calculation is reasonable. D. It may require making some reasonable assumptions in order to calculate the answer. E. It will always be accurate to at least two significant figures.

E. It will always be accurate to at least two significant figures.