1025 Physics Chapter 4

The mass of a lamb that weighs 110 N is about... a.) 11 kg b.) 1100 kg c.) 1 kg d.) 110 kg e.) none

a.) 11 kg

What horizontally-applied force will accelerate a 400-kg crate at 1 m/s2 across a factory floor against a friction force half its weight? a.) 2400 N b.) 2600 N c.) 1600 N d.) 600 N e.) none

a.) 2400 N

A 2000 kg car experiences a braking force of 10,000 N and skids to a stop in 6 seconds. The speed of the car just before the breaks were applied was... a.) 30 m/s b.) 15 m/s c.) 45 m/s d.) 1.2 m/s e.) none

a.) 30 m/s

A 1000-kg automobile enters a freeway on-ramp at 20 m/s and accelerates uniformly up to 40 m/s in a time of 10 seconds. How far does the automobile travel during that time? a.) 300m b.) 400m c.) 100m d.) 200m e.) none

a.) 300m

When a constant and sustained upward force acts on a rocket, its acceleration increases mainly because... a.) The mass of the rocket decreases as fuel is burned b.) gravity becomes weaker with increased distance c.) no way, for acceleration would be constant

a.) The mass of the rocket decreases as fuel is burned

If more horizontal force is applied to a sliding object than is needed to maintain a constant velocity, the object... a.) accelerates in the direction of the applied force b.) accelerated opposite the direction of the applied force c.) experiences greater friction d.) none of the above

a.) accelerates in the direction of the applied force

You drive your car at a constant 60 km/h along the highway. You apply the brakes until the car slows to 40 km/h. If at that moment you suddenly release the brakes, the car tends to... a.) continue moving at 40 km/h b.) momentarily regain its higher initial speed c.) decrease in speed if no other forces act

a.) continue moving at 40 km/h

A skydiver's terminal velocity will be the greatest is she falls... a.) head first b.) with her parachute open c.) lying flat on her back d.) lying flat on her stomach

a.) head first

An object with twice as much mass as another object has twice as much... a.) inertia b.) acceleration due to gravity c.) speed d.) all

a.) inertia

A skydiver steps from a helicopter and falls for a few seconds until terminal velocity is reached. Thereafter, until he opens his parachute, his acceleration... a.) is zero b.) decreases c.) is constant d.) increases e.) none

a.) is zero

Whenever the net force on an object is zero, its acceleration... a.) is zero b.) may be more than zero c.) may be less than zero

a.) is zero

Two factors that greatly affect air resistance on falling objects are frontal area and... a.) speed b.) weight c.) mass

a.) speed

your weight measured on your bathroom scale is... a.) the force of gravity on you b.) a property of mechanical equilibrium c.) equal to your mass d.) all

a.) the force of gravity on you

An apple weights 1 N. When held at rest above your head, the net force on the apple is... a.) 9.8 N b.) 0 N c.) 1 N d.) 0.1 N e.) none of the above

b.) 0 N

Strange as it may seem, it is just as difficult to accelerate a car on a level surface on the moon as it is here on the Earth because... a.) the mass of an object is independent of gravity b.) the weight of the car is independent of gravity c.) both of these d.) neither of these

a.) the mass of an object is independent of gravity

The force required to maintain a constant velocity for an astronaut in free space is equal to... a.) zero b.) the mass of the astronaut c.) the weight of the astronaut d.) the force required to stop the astronaut e.) none

a.) zero

A boulder following a straight-line path at constant velocity has... a.) zero acceleration b.) no forces acting on it c.) a net force acting upon it in the direction of motion d.) none

a.) zero acceleration

A sack of potatoes weighing 200 N falls from an airplane. As the velocity of fall increases, air resistance also increases. When air resistance equals 200 N, the sack's acceleration becomes... a.) 5 m/s^2 b.) 0 m/s^2 c.) infinite d.) 10 m/s^2 e.) none

b.) 0 m/s^2

A 1 kg rock that weighs 10 N is thrown straight upward at 20 m/s. Neglecting air resistance, the net force that acts on it when it's halfway to the top of its path is... a.) more than 10 N b.) 10 N c.) less than 10 N

b.) 10 N

A heavy ball hangs by a string, with a second string attached to its bottom. A quick pull on the bottom string breaks the... a.) top string b.) bottom string c.) top or bottom string

b.) bottom string

Suppose a particle is accelerated through space by a constant 10-N force. Suddenly the particle encounters a second force of 10-N in a direction opposite to that of the first force. The particle with both forces acting... a.) is brought to a halt b.) continues at the speed it had when it encountered the second force c.) decelerates gradually to a halt d.) theoretically tends to accelerate towards the speed of light e.) none

b.) continues at the speed it had when it encountered the second force

If less horizontal force is applied to a sliding object than is needed to maintain a constant velocity, the object... a.) experiences decreased friction b.) eventually slides to a stop c.) accelerated in the direction of the applied force d.) none

b.) eventually slides to a stop

When the bottom string is pulled slowly in the block-and-strings demonstration from class, tension is... a.) in the bottom string b.) in the top string due to your pull plus the weight of the ball c.) about the same in both strings

b.) in the top string due to your pull plus the weight of the ball

A ball is thrown vertically into the air. Because of air resistance, its time coming down compared to its time going up is... a.) less b.) more c.) the same

b.) more

An object's weight is properly expressed in units of... a.) meters b.) newtons c.) kilograms d.) cubic centimeters

b.) newtons

A light woman and a heavy man jump from an airplane at the same time and open their same-size parachutes at the same time. Which person will get to the ground first? a.) not enough info b.) the heavy man c.) both should arrive at the same time d.) the light woman

b.) the heavy man

A light woman and a heavy man jump from an airplane at the same time and open their same-size parachutes at the same time. Which person will get to a state of zero acceleration first? a.) the heavy man b.) the light woman c.) both d.) not enough info

b.) the light woman

Compared to the mass of an apple on earth, the mass of an apple on the moon is... a.) 1/6x as much b.) the same c.) 6x as much d.) zero

b.) the same

A 10-kg brick and a 1-kg apple are dropped in a vacuum. The force of gravity on the brick is... a.) 10 times more than the force on the apple b.) the same as the force on the apple c.) zero d.) 1/10 as much as the apple

b.) the same as the force on the apple

A 1 kg mass at the earth's surface weighs... a.) 1 N b.) 5 N c.) 10 N d.) 12 N e.) none

c.) 10 N

A tow truck exerts a force of 2000 N on a car, accelerating it at 1 m/s/s. What is the mass of the car? a.) 3000 kg b.) 1000 kg c.) 1500 kg d.) 500 kg e.) none

c.) 1500 kg

Nellie pulls on a 10-kg wagon with a constant horizontal force of 30 N. If there are no other horizontal forces, what is the wagon's acceleration? a.) 0.3 m/s^2 b.) 30 m/s^2 c.) 3.0 m/s^2 d.) 300 m/s^2 e.) 10 m/s^2

c.) 3.0 m/s^2

A 300 kg bear grasping a vertical tree slides down at a constant velocity. The friction force between the tree and the bear is... a.) 30 N b.) 300 N c.) 3000 N d.) more than 3000 N

c.) 3000 N

An astronaut on another planet drops a 1-kg rock from rest and finds that it falls a vertical distance of 2.5 meters in one second. On this planet, the rock has a weight of... a.) 1 N b.) 2 N c.) 5 N d.) 3 N e.) 4 N

c.) 5 N

a 10 N falling object encounters 4 N of air resistance. The net force on the object is... a.) 0 N b.) 4 N c.) 6 N d.) 10 N e.) none

c.) 6 N

If an apple experiences a constant net force, it will have a constant... a.) velocity b.) speed c.) acceleration d.) position e.) more than one of the above

c.) acceleration

A coconut and a bird's feather fall from a tree through the air to the ground below. The force of air resistance is... a.) greater on the feather b.) the same on each c.) greater on the coconut

c.) greater on the coconut

A heavy block at rest is suspended by a vertical rope. When the block accelerates upward by the rope, the rope tension is... a.) less than its weight b.) equals its weight c.) greater than its weight

c.) greater than its weight

Two tennis balls fall through the air from a tall building. One of them is filled with lead pellets. The ball to reach the ground first is the... a.) regular ball b.) same for both c.) lead-filled ball

c.) lead-filled ball

A rock weighs 30 N on Earth. A second rock weighs 30 N on the moon. Which of the two rocks has the greater mass? a.) they have the same mass b.) the one on earth c.) the one on the moon d.) not enough info

c.) the one on the moon

An object released from rest on another planet requires one second to fall a distance of 6 meters. What is the acceleration due to gravity on this planet? a.) 15 m/s^2 b.) 3 m/s^2 c.) 6 m/s^2 d.) 12 m/s^2 e.) none

d.) 12 m/s^2

A car has a small mass of 1000 kg and accelerates at 2 m/s^2. What is the net force exerted on the car? a.) 500 N b.) 1000 N c.) 1500 N d.) 2000 N e.) none

d.) 2000 N

A mobile phone is pulled northward by a force of 10 N and at the same time pulled southward by another force of 15 N. The resultant force on the phone is... a.) 150 N b.) 0 N c.) 25 N d.) 5 N

d.) 5 N

Suzie Skydiver, who weighs 500 N, reaches terminal velocity of 90 km/h. The air resistance on Suzie is then... a.) 90 N b.) 250 N c.) 410 N d.) 500 N e.) none

d.) 500 N

Compared to a 1-kg block of solid iron, a 2-kg block of solid iron has twice as much... a.) inertia b.) mass c.) volume d.) all of the above e.) none

d.) all of the above

A large and a small person wish to parachute at equal terminal velocities. The larger person will have to a.) jump lightly b.) pull upward on the supporting strands to decrease the downward net force c.) jump first from the plane d.) get a larger parachute

d.) get a larger parachute

If the mass of a cart is quickly loaded to have twice the mass while a propelling force remains constant, the cart's acceleration... a.) quadruple b.) doubles c.) stays the same d.) halves e.) none

d.) halves

A feather and a coin will have equal accelerations when falling in a vacuum because... a.) The force of gravity does not act in a vacuum b.) the force of gravity is the same for each in a vacuum c.) the velocities are the same d.) the ratio of both the feather's and coin's weight to mass is the same e.) none

d.) the ratio of both the feather's and coin's weight to mass is the same