PHYS-1405 HOMEWORK 3

A cart maintains a constant velocity of 100 m/s for 10 seconds. During this interval its acceleration is zero. 10 m/s2. 1 m/s2. none of the above

zero

An object falls freely from rest on a planet where the acceleration due to gravity is twice as much as on Earth. In the first 5 seconds it falls a distance of 250 m. 100 m. 150 m. 500 m. none of the above

250 m

An apple weighs 1 N. When the apple is held at rest above your head, the net force on the apple is 9.8 N. 0.1 N. 1 N. 0 N. none of the above

0 N

A mosquito flying at 3 m/s that encounters a breeze blowing at 3 m/s in the opposite direction has a speed of 6 m/s. 3 m/s. 4 m/s. 0 m/s.

0 m/s

An apple falls from a tree and hits the ground 5 meters below with a speed of about 10 m/s. 15 m/s. 20 m/s. 5 m/s. not enough information

10 m/s

A bag of groceries that has a mass of 10 kilograms weighs about greater than 1000 N. 1 N. 10 N. 100 N. 1000 N.

100 N

A river 100 m wide flows due south at 1 m/s. A boat that travels 1 m/s relative to the water is pointed due east as it crosses from the west bank. The boat reaches the east bank 141 m farther south. due east of its starting point. 100 m farther south. none of the above

100 m farther south

The mass of a lamb that weights 110 N is about 110 kg. 1 kg. 11 kg. 1100 kg. none of the above

11 kg

Jogging Jake runs at 4 m/s along a train flatcar that moves at 10 m/s in the same direction. Jake's speed relative to the ground is 10 m/s. 6 m/s. 14 m/s. none of the above

14 m/s

A tow truck exerts a force of 3000 N on a car, which then accelerates at 2 m/s2. What is the mass of the car? 1500 kg 500 kg 3000 kg 1000 kg none of these

1500 kg

An object at rest near the surface of a distant planet starts to fall freely. If the acceleration there is twice that of the Earth, its speed one second later would be 10 m/s. 20 m/s. 30 m/s. 40 m/s.

20 m/s

If a freely falling object were equipped with a speedometer on a planet where the acceleration due to gravity is 20 m/s2, then its speed reading would increase each second by 40 m/s. 30 m/s. 20 m/s. 10 m/s. depends on its initial speed

20 m/s

A humming bird flying at 4 km/h that gets caught in a 3-km/h crosswind has a resultant speed of about 3 km/h. 5 km/h. more than 5 km/h. 4 km/h.

5 km/h

In which case would you have the largest mass of gold? If your chunk of gold weighed 1 N on the Moon. planet Jupiter. Earth.

Moon

The attraction between Earth and Sydney is equal to her weight. The reaction to Earth's pull on Sydney is Sydney pushing against Earth's surface. Sydney's pull on Earth. the support of Earth's surface on Sydney. none of the above

Sydney's pull on Earth

A seagull flying at 10 km/h in a 10-km/h crosswind has a resultant speed of about 14 km/h. 10 km/h. more than 20 km/h. 20 km/h.

about 14 km/h

A freely-falling watermelon falls with constant acceleration. velocity. speed. distances each successive second.

acceleration

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

acceleration

You're at rest in a hammock when a hungry mosquito sees an opportunity for lunch. A mild 2-m/s breeze is blowing. If the mosquito joins you for lunch it should hover over you by flying with the breeze at 2 m/s. against the breeze at 2 m/s. a bit faster than wind speed. none of the above

against the breeze at 2 m/s

A vehicle undergoes acceleration when it changes its direction. loses speed. gains speed. all of the above

all of the above

Action and reaction pairs of forces happen one after the other. always act simultaneously. may or may not act simultaneously.

always act simultaneously

Which has the greater mass? an automobile battery a king-size pillow both the same

an automobile battery

If an object moves with constant acceleration, its velocity must be constant also. always decrease. change by varying amounts depending on its speed. change by the same amount each second.

change by the same amount each second

Katelyn runs along the aisle of a train that moves at 8 m/s. Her speed relative to the floor is 3 m/s. Her speed relative to an observer at rest on the ground is 11 m/s. 5 m/s. either depending on her running direction none of the above

either depending on her running direction

The newton is a unit of force. inertia. density. mass.

force.

A heavy rock and a light rock of the same size are falling through the air from a tall building. The one that encounters the greatest air resistance is the heavy rock. same for both light rock.

heavy rock

The distance a freely falling bowling ball falls each second is about 10 m. is about 5 m. increases. none of the above

increases

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

is zero

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 same for both lead-filled ball. regular ball.

lead-filled ball

Twelve seconds after starting from rest, a freely-falling cantelope has a speed of 100 m/s. more than 100 m/s. 50 m/s. 10 m/s.

more than 100 m/s

An object's weight is properly expressed in units of meters. newtons. cubic centimeters. kilograms.

newtons

Compared to a 1-kg block of solid iron, a 2-kg block of solid iron has the same weight. mass. volume. all of the above none of the above

none of the above

The distance a freely falling object falls from rest in one-half second is 4 m. 6 m. 2 m. none of the above

none of the above

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 Earth because the mass of the car is independent of gravity. the weight of the car is independent of gravity. both of these neither of these

the mass of the car is independent of gravity

A rock weighs 30 N on Earth and another rock weighs 30 N on the Moon. Which rock has the greater mass? They have the same mass. the one on Earth the one on the Moon not enough information

the one on the Moon

Compared to the mass of an apple on Earth, the mass of the apple on the Moon is six times as much. zero. one sixth as much. the same.

the same

Earth pulls on the Moon, and the Moon pulls on Earth, which tells us that they will collide. these two pulls comprise an action-reaction pair. more massive objects pull harder. all of the above

these two pulls comprise an action-reaction pair