PHY201 Clicker Questions

On a rotating carousel or merry-go-round, one child sits on a horse near the outer edge and another child sits on a lion halfway out from the center. (a)Which child has the greater linear velocity? horse or lion? (b)Which child has the greater angular velocity?

(a) horse (b) travel the same angel.

A child sits in a wagon moving to the right at constant speed. She throws an apple straight upward (from her own point of view), while the wagon continues to travel forward at constant speed. If air resistance is neglected, will the apple land (a) behind the wagon, (b) in the wagon (c) in front of the wagon

(b) in the wagon.

An empty sled is sliding on frictionless ice when Susan drops vertically from a tree above onto the sled. When she lands, does the sled: (a) speed up (b) slow down (c) keep the same speed?

(b) slow down

Later, Susan falls sideways off the same sled. When she drops off, does the sled: (a) speed up (b) slow down (c) keep the same speed

(c) keep the same speed

The Moon revolves around the Earth in a nearly circular orbit, with approximately constant tangential speed, kept there by the gravitational force exerted by the Earth. Does gravity do... (a)positive work, (b) negative work (c) no work at all on the Moon?

(c)no work at all on the Moon? Gravity does no work on the Moon, as the force is always perpendicular to the displacement (assuming a circular orbit).

The gravitational force between two asteroids is 1,000,000 N. What will the force be if the distance between the asteroids is doubled? A. 250,000 N. B. 500,000 N. C. 1,000,000 N. D. 2,000,000 N. E. 4,000,000 N.

A. 250,000 N.

The top block is accelerated across a frictionless table by the falling mass m. The string is massless, and the pulley is both massless and frictionless. The tension in the string is A. T < mg. B. T = mg. C. T > mg

A. T < mg (Tension has to be less than mg for the block to have a downward acceleration.)

A mosquito runs head-on into a truck. Which is true during the collision? A. The magnitude of the mosquito's acceleration is larger than that of the truck. B. The magnitude of the truck's acceleration is larger than that of the mosquito. C. The magnitude of the mosquito's acceleration is the same as that of the truck. D. The truck accelerates but the mosquito does not. E. The mosquito accelerates but the truck does not.

A. The magnitude of the mosquito's acceleration is larger than that of the truck.

An object on a rope is lowered at a steadily decreasing speed. Which is true? A. The rope tension is greater than the object's weight. B. The rope tension equals the object's weight. C. The rope tension is less than the object's weight. D. The rope tension can't be compared to the object's weight.

A. The rope tension is greater than the object's weight.

A ball rolls down an incline and off a horizontal ramp. Ignoring air resistance, what force or forces act on the ball as it moves through the air just after leaving the horizontal ramp? A. The weight of the ball acting vertically down. B. A horizontal force that maintains the motion. C. A force whose direction changes as the direction of motion changes. D. The weight of the ball and a horizontal force. E. The weight of the ball and a force in the direction of motion.

A. The weight of the ball acting vertically down.

Robert pushes the box to the left at constant speed. In doing so, Robert does ______ work on the box. A. positive B. negative C. zero

A. positive Force is in the direction of displacement ⇒ positive work

At t = 1.5 s, the object's velocity is A) 40 m/s B) 20 m/s C) 10 m/s D) -10 m/s E) None of the above.

B) 20 m/s (Find the slope of the point before and after: slope = (y_2 - y_1 ) / ( x_2 - x_1)

The 1 kg box is sliding along a frictionless surface. It collides with and sticks to the 2 kg box. Afterward, the speed of the two boxes is A. 0 m/s. B. 1 m/s. C. 2 m/s. D. 3 m/s. E. There's not enough information to tell.

B. 1 m/s. m1vi + m2vi = (m1 + m2)vf

The two boxes are on a frictionless surface. They had been sitting together at rest, but an explosion between them has just pushed them apart. How fast is the 2 kg box going? A. 1 m/s. B. 2 m/s. C. 4 m/s. D. 8 m/s. E. There's not enough information to tell

B. 2 m/s. 0 = m1vf + m2vf

A constant force causes an object to accelerate at 4 m/s2. What is the acceleration of an object with twice the mass that experiences the same force? A. 1 m/s2. B. 2 m/s2. C. 4 m/s2. D. 8 m/s2. E. 16 m/s2.

B. 2 m/s^2

A steel beam hangs from a cable as a crane lifts the beam. What forces act on the beam? A. Gravity. B. Gravity and tension in the cable. C. Gravity and a force of motion. D. Gravity and tension and a force of motion.

B. Gravity and tension in the cable.

A box with a weight of 100 N is at rest. It is then pulled by a 30 N horizontal force. Does the box move? u_s = .4 u_k = .2 A. Yes B. No C. Not enough information to say.

B. No (The f_s is equal to 40.)

A hockey puck sliding on smooth ice at 4 m/s comes to a 1-m-high hill. Will it make it to the top of the hill? A. Yes. B. No. C. Can't answer without knowing the mass of the puck. D. Can't say without knowing the angle of the hill

B. No. 1/2mv^2 = mgh v^2 = 2gh == 20m/s

Projectiles 1 and 2 are launched over level ground with the same speed but at different angles. Which hits the ground first? Ignore air resistance. A. Projectile 1 hits first. B. Projectile 2 hits first. C. They hit at the same time. D. There's not enough information to tell.

B. Projectile 2 hits first. (The y-direction is how you determine the time to impact. If a projectile goes higher in the air, it takes longer to land. (Consider symmetry and vertical free-fall from rest) )

Two coins rotate on a turntable. Coin B is twice as far from the axis as coin A. A. The angular velocity of A is twice that of B. B. The angular velocity of A equals that of B. C. The angular velocity of A is half that of B

B. The angular velocity of A equals that of B.

An object on a rope is lowered at constant speed. Which is true? A. The rope tension is greater than the object's weight. B. The rope tension equals the object's weight. C. The rope tension is less than the object's weight. D. The rope tension can't be compared to the object's weight.

B. The rope tension equals the object's weight.

An object on a rope is lowered at a steadily decreasing speed. Which is true? A. The rope tension is greater than the object's weight. B. The rope tension equals the object's weight. C. The rope tension is less than the object's weight. D. The rope tension can't be compared to the object's weight

B. The rope's tension equals the object's weight.

A crane lowers a girder into place at constant speed. Consider the work Wg done by gravity and the work WT done by the tension in the cable. Which is true? A. Wg > 0 and WT > 0 B. Wg > 0 and WT < 0 C. Wg < 0 and WT > 0 D. Wg < 0 and WT < 0 E. Wg = 0 and WT = 0

B. Wg > 0 and WT < 0 The downward force of gravity is in the direction of motion ⇒ positive work. The upward tension is in the direction opposite the motion ⇒ negative work.

A light plastic cart and a heavy steel cart are both pushed with the same force for a distance of 1.0 m, starting from rest. After the force is removed, the kinetic energy of the light plastic cart is ________ that of the heavy steel cart. A. greater than B. equal to C. less than D. Can't say. It depends on how big the force is.

B. equal to same force means same work meaning same change of kinetic energy.

A ball is tossed straight up in the air. At it's very highest point ,the ball's acceleration vector a... A) Points up. B) is Zero C)Points down

C) points down *In fact, the acceleration vector points down as the ball rises, at the highest point, and as it falls.

The two boxes are sliding along a frictionless surface. They collide and stick together. Afterward, the velocity of the two boxes is A. 2 m/s to the left. B. 1 m/s to the left. C. 0 m/s, at rest. D. 1 m/s to the right. E. 2 m/s to the right.

C. 0 m/s, at rest.

You stand motionless on the ground. The force of gravity, (FG), pulls you down, and the floor pushes up with a normal force, (n). Which of the following is true? A. FG and n are not an action/reaction pair because they are not equal in magnitude. B. FG and n are an action/reaction pair because they are equal in magnitude and opposite in direction. C. FG and n are not an action/reaction pair because they are both forces operating on the same object. D. There isn't enough information to know if FG and n are an action/reaction pair or not.

C. FG and n are not an action/reaction pair because they are both forces operating on the same object.

A box is being pulled to the right at steady speed by a rope that angles upward. In this situation: A. FN > mg. B. FN = mg. C. FN < mg. D. FN = 0. E. Not enough information to judge the size of the normal force.

C. FN < mg.

Starting from rest, a marble first rolls down a steeper hill, then down a less steep hill of the same height. For which is it going faster at the bottom? (Ignore friction, for now) A. Faster at the bottom of the steeper hill. B. Faster at the bottom of the less steep hill. C. Same speed at the bottom of both hills. D. Can't say without knowing the mass of the marble.

C. Same speed at the bottom of both hills.

Boxes A and B are being pulled to the right on a frictionless surface. Box A has a larger mass than B. How do the two tension forces compare? QuickCheck Slide 7-61 A. T1 > T2 B. T1 = T2 C. T1 < T2 D. Not enough information to tell.

C. T1 < T2

A mosquito runs head-on into a truck. Splat! Which is true during the collision? A. The mosquito exerts more force on the truck than the truck exerts on the mosquito. B. The truck exerts more force on the mosquito than the mosquito exerts on the truck. C. The mosquito exerts the same force on the truck as the truck exerts on the mosquito. D. The truck exerts a force on the mosquito but the mosquito does not exert a force on the truck. E. The mosquito exerts a force on the truck but the truck does not exert a force on the mosquito.

C. The mosquito exerts the same force on the truck as the truck exerts on the mosquito.

The force of Planet Y on Planet X is ___ the magnitude of . A. One quarter. B. One half. C. The same as. D. Twice. E. Four times.

C. The same as.

A mosquito and a truck have a head-on collision. Splat! Which has a larger change of momentum? A. The mosquito. B. The truck. C. They have the same change of momentum. D. Can't say without knowing their initial velocities.

C. They have the same change of momentum.

A heavy ball (A) is launched exactly horizontally at height h above a horizontal field. At the exact instant that the ball is launched, a second ball (B) is simply dropped from height h. Which ball hits the ground first? A. Ball A hits first. B. Ball B hits first. C. They hit at the same time. D. Neither ball hits the ground

C. They hit at the same time.

A heavy red ball is released from rest 2.0 m above a flat, horizontal surface. At exactly the same instant, a yellow ball with the same mass is fired horizontally at 3.0 m/s. Which ball hits the ground first? A. The red ball hits first. B. The yellow ball hits first. C. They hit at the same time.

C. They hit at the same time.

Projectiles 1 and 2 are launched over level ground with different speeds. Both reach the same height. Which hits the ground first? Ignore air resistance. A. Projectile 1 hits first. B. Projectile 2 hits first. C. They hit at the same time. D. There's not enough information to tell.

C. They hit at the same time.

Three balls are thrown from a cliff with the same speed but at different angles. Which ball has the greatest speed just before it hits the ground? A. Ball A. B. Ball B. C. Ball C. D. All balls have the same speed.

D. All balls have the same speed.

A bobsledder pushes her sled across horizontal snow to get it going, then jumps in. After she jumps in, the sled gradually slows to a halt. What forces act on the sled just after she's jumped in? A. Gravity and kinetic friction. B. Gravity and a normal force. C. Gravity and the force of the push. D. Gravity, a normal force, and kinetic friction. E. Gravity, a normal force, kinetic friction, and the force of the push

D. Gravity, Normal Force, and Kinetic Friction.

A small child slides down the four frictionless slides A-D. Rank in order, from largest to smallest, her speeds at the bottom. A. vD > vA > vB > vC B. vD > vA = vB > vC C. vC > vA > vB > vD D. vA = vB = vC = vD

D. vA = vB = vC = vD

The fan blade is speeding up. What are the signs of ω and α? A. ω is positive and α is positive. B. ω is positive and α is negative. C. ω is negative and α is positive. D. ω is negative and α is negative.

D. ω is negative and α is negative. if ω is negative then α is negative as well.

A box is being pulled to the right over a rough surface. T > fk, so the box is speeding up. Suddenly the rope breaks. What happens? The box A. Stops immediately. B. Continues with the speed it had when the rope broke. C. Continues speeding up for a short while, then slows and stops. D. Keeps its speed for a short while, then slows and stops. E. Slows steadily until it stops .

E. Slows steadily until it stops.

An ice hockey puck is tied by a string to a stake in the ice. The puck is then swung in a circle. What force is producing the centripetal acceleration of the puck? A. Gravity B. Air resistance C. Friction D. Normal force E. Tension in the string

E. Tension in the string

Two water slides at a pool are shaped differently, but start at the same height h. Two riders, Paul and Kathleen, start from rest at the same time on different slides. Which rider makes it to the bottom first? Paul or Kathleen? Ignore friction and assume both slides have the same path length.

Kathleen

If the acceleration is zero, does it mean that the velocity is zero? Yes or No?

No.

If the velocity of an object is zero, does it mean that the acceleration is zero? Yes or No?

No.

A car is traveling around a curve at a steady 45 mph (speed). Which vector shows the direction of the car's acceleration?

Towards the center.

A car is traveling around a curve at a steady 45 mph. Is the car accelerating? A. Yes B. No

Yes.

A hunter in the jungle wants to shoot down a coconut that is hanging from the branch of a tree. He points his arrow directly at the coconut, but the coconut falls from the branch at the exact instant the hunter shoots the arrow. Does the arrow hit the coconut?

Yes.

A box on a rough surface is pulled by a horizontal rope with tension T. The box is not moving. In this situation: A. fs > T. B. fs = T. C. fs < T. D. fs = µsmg. E. fs = 0

fs = T.