physics 002a definitions

Two identical stones are dropped from a tall building, one after the other. Assume air resistance is negligible. While both stones are falling, what will happen to the vertical distance between them?

A) It will increase

If you stood on a planet having a mass four times higher than Earth's mass, and a radius two times longer than Earth's radius, you would weigh

A) The same as you do on earth

Three cars, Car X, Car Y, and Car Z, begin accelerating from rest, at the same time. Car X is more massive than Car Y, which is more massive than Car Z. The net force exerted on each car is identical. After 10 seconds, which car has the most amount of momentum?

A) They all have the same momentum

Shown here are the velocity and acceleration vectors for an object in several different types of motion. In which case is the object's velocity changing while its speed is not changing?

A) acceleration up, velocity-->

A small mass is placed on a record turntable that is rotating at 45 rpm. The linear acceleration of the mass is

A) greater the farther the mass is from center

Torque

a turning or twisting force

Suppose that a heavy person and a light person are balanced on a teeter-totter made of a plank of wood. Each person now moves in toward the fulcrum a distance of 25 cm. What effect will this have on the balance of the teeter-totter?

a) the light person end goes down

Two blocks, A and B, are being pulled to the right along a horizontal surface by a horizontal 100 N pull, as shown in the figure. Both of them are moving together at a constant velocity of 2.0 m/s to the right, and both weigh the same. Which of the figures below shows a correct free-body diagram of the horizontal forces acting on upper block, A?

B) no horizontal forces acting on A

(17) A block of mass m sits at rest on a rough inclined ramp that makes an angle θ with the horizontal. What must be true about normal force F on the block due to the ramp?

D) F = mg cos θ

(5) Which statement is true:

D. When acceleration is finite, it is possible to maintain constant speed (magnitude of velocity).

(15) Which of the following statement is correct?

E) A pair of action and reaction forces are always applied on different objects.

(8) A crate is sliding down an inclined ramp at a constant speed of 0.55 m/s. The vector sum of all the forces acting on this crate must point

E) None of the above choices is correct.

Non-zero velocity ex:

a car is under straight-line uniform motion, moving with a non-zero constant velocity of 80 km / h . In this case, the acceleration is zero as there is no change in velocity.

6) A ball can be rolled down one of four different ramps, as shown below. The final elevation loss of each of the ramps is the same. Neglecting friction, for which ramp will the speed of the ball be the highest at the bottom?

a)the speed of the ball is the same for all ramps

angular momentum

Product of rotational inertia and rotational velocity

Joe and Bill throw identical balls vertically upward. Joe throws his ball with an initial speed of twice as high as Bill's ball. The maximum height of Joe's ball will be

D)four times that of Bill's ball.

In the figure, a given force F is applied to a rod in several different ways. In which case is the torque due to F about the pivot P greatest?

A)1

which of the following situations is impossible?

A)An object has constant non-zero velocity and changing acceleration

A block is at rest on a rough incline as shown The frictional force acting on the block, along the incline, is

A)Less than weight of block

A cyclist is riding up a hill having a constant slope of 30° with respect to the horizon at a constant speed (in a straight line). Which statement is true?

A)The net force on the bike(due to gravity, the normal force, and friction) is zero.

You need to make a sharp turn on a flat road, making a radius of curvature of 15 meters. How does the required force of static friction between your tires compare if you make the turn at 30 mph vs. 60 mph?

A)the force of friction needs to be 4 times as large

(1) At which point does the speed decrease? Please note that speed means the magnitude of the velocity.

A, because from A-->B goes from positive to zero

(9) A 20-ton truck collides with a 1500-lb car. Which of the following statements must be true?

B) During the collision, the force on the truck is equal to the force on the car.

(16) A push of magnitude P acts on a box of weight W as shown in the figure. The push is directed at an angle θ below the horizontal line, and the box remains at rest. The box rests on a horizontal surface that has some friction with the box. The friction force on the box due to the floor is equal to:

B) P cos θ

Two cyclists, who weigh the same and have identical bicycles, ride up the same mountain, both starting at the same time. Joe rides straight up the mountain, and Bob rides up the longer road that has a lower grade. Joe gets to the top before Bob. Which statement is true

B)Ignoring friction and wind resistance, the amount of work done by Joe is equal to the amount of work done by Bob, but the average power exerted by Joe is greater than that of Bob

Under what condition is average velocity equal to the average of the object's initial and final velocity?

B)The acceleration must be constantly decreasing

Consider what happens when you jump up in the air. Which of the following is the most accurate statement?

B)When you push down on the earth with a force greater than your weight, the earth will push back with the same magnitude force and thus propel you into the air

You are standing on a skateboard, initially at rest. A friend throws a very heavy ball toward you. You can either catch the object or deflect the object back toward your friend (such that it moves away from you with the same speed as it was originally thrown). What should you do in order to maximize your speed on the skateboard?

B)deflect the ball back

) The figure shows two forces acting on an object. They have magnitudesF1 = 9.6 N andF2 = 3.2 N. What third force will cause the object to be in equilibrium?

C) 10N @ 162 counterclockwise from F1

A tire is rolling along a road, without slipping, with a velocity v. A piece of tape is attached to the tire. When the tape is opposite the road (at the top of the tire), it's velocity with respect to the road is

C) 2V

(13) A piano mover raises a 1000-N piano at a constant speed using a very light rope in a frictionless pulley system, as shown in the figure. With what force is the mover pulling down on the rope?

C) 500 N

If an astronaut were exactly halfway between Earth and the Moon, the net gravitational force exerted on the astronaut by these two objects would be

C) directed towards earth

Bob and Biff throw identical rocks off a tall building at the same time. Bob throws his rock straight downward. Biff throws his rock downward and outward such that the angle between the initial velocity of the rock and the horizon is 30 degrees. Biff throws the rock with a speed twice that of Bob's rock. Which rock hits the ground first (assume the ground near the building is flat)?

C) they hit at the same time

If you were to move into outer space far from any stars or planets,

C) your weight would change,but your mass would not change

Consider two less-than-desirable options. In the first you are driving 30 mph and crash head-on into an identical car also going 30 mph. In the second option you are driving 30 mph and crash head-on into a stationary brick wall. In neither case does your car bounce off the thing it hits, and the collision time is the same in both cases. Which of these two situations would result in the greatest impact force?

C)The force would be the same in both cases

In the figure, determine the character of the collision. The masses of the blocks, and the velocities before and after are given. The collision is:

C)completely inelastic

Suppose a ball is thrown straight up and experiences no appreciable air resistance. What is its acceleration when it reaches its highest point?

C)slightly greater than g

A rock is thrown from the upper edge of a tall cliff at some angle above the horizontal. It reaches its highest point and starts falling down. Which of the following statements about the rock's motion are true just before it hits the ground?

D) Its horizontal velocity component is the same as it was just as it was launched.

If you jumped out of a plane, you would begin speeding up as you fall downward. Eventually, due to wind resistance, your velocity would become constant with time. After this occurs, the magnitude of the force of wind resistance is

D)equal to the force of gravity acting on you

(11) Three boxes are pulled along a horizontal frictionless floor by a constant horizontal pull P. The boxes are connected by very light horizontal strings having tensions T1 and T2 as shown in the figure. Which of the following statements about the tensions is correct?

E)T1 > T2

(12) Which of the following object has zero net force?

c)A man at the terminal speed when he is falling

angular velocity

The angular displacement of an object divided by the time needed to make the displacement.

objects dropped at the same time will hit the ground?

at the same time no matter the weights, because Earths gravity is the same.

Two bodies P and Q on a perfectly smooth horizontal surface are connected by a light cord. The mass of P is greater than that of Q. A horizontal force F is applied to Q as shown in the figure, accelerating the bodies to the right.

b) less than F but not zero

(7) When a book is put on a tilted table, it is sliding slowly downward. What is the reaction force of its weight?

b)The gravitational force acting on the earth from the book

(6) Which of the following statements is wrong?

d. The astronauts have weightless experience in the space station, because the gravity is zero there.

angular momentum equation

mass x velocity x radius

Torque equation

r=length of the lever arm F=magnitude of the force Ѳ= angel between the lever arm and force vectors

Non-zero velocity

the change in the velocity is still taking place when the velocity of the object reaches zero.

angular velocity equation

ω = θ/t