Physics

The graph in the figures shows th x component F of the net force that acts for 10 s on a 100-kg crate. What is the change in the momentum of the crate during the 10 s that this force acts?

-75 kg *m/s

A 35-N bucket of water is lifted vertically 3.0 m and then returned to its original position. How much work did gravity do on the bucket during this process?

0 J

A 50.0 kg crate is being pulled along a horizontal smooth surface. The pulling force is 10.0 N and is directed 20.0 degrees above the horizontal. What is the magnitude of the acceleration of the crate?

0.188 m/s2

A 0.330 kg volleyball is thrown vertically downward with a speed of 0.150 m/s in a place where g=9.81 m/s2. It takes it 0.0655 s to reach the ground. What is the magnitude of its momentum just before it hits the ground?

0.262 kg *m/s

Two ice skaters suddenly pus off against one another starting from a stationary position. The 45-kg skater acquires a speed of 0.375 m/s relative to the ice. What speed does the 60-kg skater acquire?

0.28 m/s

The length and width of a rectangle are 1.125 m and 0.606 m, respectively. Multiplying your calculator gives you the product as 0.68175. Rounding properly to the correct number of significant figures, the area of the rectangle should be written as

0.682 m2

An athlete competing in the long jump leaves the ground with a speed of 9.14 m/s at an angle of 30 degrees above the horizontal. How long does the athlete stay in the air, assuming no significant air resistance?

1.1 second

A 100-g ball falls from a window that is 12 m above ground level and experiences no significant air resistance as it falls. What is its momentum when it strikes the ground?

1.5 kg * m/s

In a police ballistics test, a 10.0-g bullet moving at 300 m/s is fired into a 1.00-kg block at rest. The bullet goes through the block almost instantaneously and emerges with 50.0% of its original speed. What is the speed of the block just after the bullet emerges?

1.50 m/s

A 0.140-kg baseball is dropped from rest from a height of 2.20 m above the ground and experiences negligible air resistance as it falls. It rebounds to a height of 1.60 m. What change in the ball's momentum occurs as it rebounds from the ground?

1.70 kg * m/s upwards

A 2.0-kg ball moving eastward at 3.0 m/s suddenly collides with and sticks to a 4.0-kg ball moving northward at 2.0 m/s. What is the magnitude of the momentum of this system just after the collision?

10 kg * m/s

A policeman investigating an accident measures the skid marks left by a car on the horizontal road. He determines that the distance between the point that the driver slammed on the brakes (thereby locking the wheels) and the point where the car came to a stop was 28.0 m. From a reference manual he determines that the coefficient of kinetic friction between the tires and the road under the prevailing conditions was 0.300. How fast was the car going when the driver applied the brakes?

12.8 m/s

A 900-kg car traveling east at 15.0 m/s suddenly collides with a 750-kg car traveling north at 20.0 m/s. The cars stick together after the collision. What is the speed of the wreckage just after the collision?

12/2 m/s

A projectile is fired from ground level with a speed of 150m/s at an angle of 30 degrees above the horizontal on an airless planet where g= 10m/s2. What is the horizontal component of its velocity after 4 seconds?

130 m/s

A car heading north suddenly collides at an intersection with a truck of the same mass heading east. If they lock together and travel 28 m/s at 15 degrees north of east just after the collision, how fast was the car initially traveling?

14 m/s

To get to her physics class, Alice walks 0.25 mi to the bus stop. She takes the bus 1.2 mi to the train station. She takes the train 13 mi and walks the remaining 0.17 mi to her class. How far is her commute expressed to the correct number of significant figures?

15 mi

You are driving home on a weekend from school at 55 mi/h for 110 miles. It then starts to snow and you slow to 35 mi/h. You arrive home after driving 4 hours and 15 minutes. How far is your hometown from school

190 miles

a 1200-kg cannon suddenly fires a 100-kg cannonball at 35 m/s. What is the recoil speed of the cannon? Assume that frictional forces are negligible and the cannon is fired horizontally.

2.9 m/s

The figure shows a famous roller coaster ride. You can ignore friction. If the roller coaster leaves point Q from rest, what is its speed at the top of the 25-m peak (point S)?

22 m/s

A 0.140-kg baseball is dropped from rest. It has a speed of 1.20 m/s just before it hits the ground and it rebounds with an upward speed of 1.00 m/s. The ball is in contact with the ground for 0.0140 s. What is the average force exerted by the ground on the ball during the time of contact?

22.0 N upwards

A player throws a football 50 m at 61 degrees north of west. What is the westward component of displacement of the football?

24.2 meters

A 400-kg box is lifted vertically upward with constant velocity by means of two cables pulling at 40.0 degres on either side of the vertical direction. What is the tension in each cable.

2560 N

A car travels 20 km west and then 20 km south. What is the magnitude of its displacement vectors.

28 km

Aver light ideal spring stretches by 21.0 cm when it is sued to hang a 135 - N object. What is the weight of a piece of electronic equipment that would stretch the spring by 44.9 cm if you hung the equipment using the spring.

289 N

How much kinetic energy does a 0.30-kg stone have if it is thrown at 44 m/s?

290 J

An object initially at rest suddenly explodes in two fragments of masses 2.6 kg and 3.23kg that move in opposite directions. If the speed of the first fragment is 3.6 m/s find the internal energy of the explosion.

30 J

An astronaut stands at the rim of a crater on the moon, where the acceleration of gravity is 1.62 m/s2 and there is no air. To determine the depth of a crater, she drops a rock and measures the time it takes for it to hit the bottom. If the time is 6.3s, what is the depth of the crater?

32 meters

What magnitude net force is required to accelerate a 1200-kg car uniformly from 0 m./s to 27.0 m/s in 10 seconds.

3240 N

A 450-kg sports care accelerates from rest to 100 km/h in 4..8 seconds. What magnitude force does a 68.0 kg passenger experience during the acceleration?

394N

An airplane increases its speed at the average rate of 15 m/s2. How much time does it take to increase its speed from 100 m/s to 160 m/s?

4 seconds

A polar bear starts at the North Pole. It travels 1.0 km south, then 1.0 km east, and then 1.0 kn north to return to its starting point. This trip takes 45 minutes. What was the bear's average speed?

4.0 km/h

On an alien planet, an object moving at 4.0 m/s on the horizontal ground comes to rest after traveling a distance of 10m. If the coefficient of kinetic friction between the object and the surface is 0.20, what is the value of g on that planet?

4.0 m/s2

A car initially travelling at 60 km/h accelerates at a constant rate of 2 m/s2. How much time is required for the car to reach a speed of 90 km/s?

4.2s

A 0.10 kg ball, traveling horizontally at 25 m/s, strikes a wall and rebounds at 19 m/s. What is the magnitude of the change in the momentum of the ball during the rebound?

4.4 kg * m/s

A crane lifts a 425 kg steel beam vertically upward a distance of 93m . How much work does the crane do on the beam if the beam accelerates upward at 1.8 m/s2? Neglect frictional forces.

4.7 = 10 ^5 J

A 0.140 kg baseball is thrown horizontally with a velocity of 28.9 m/s. It is struck with a constant horizontal force that lasts for 1.85 ms, which results in a velocity of 37.0 m/s in the opposite direction. What was the magnitude of the horizontal force?

4.99 kN

A 0.24 kg blob of clay is thrown at a wall with an initial horizontal velocity of 16 m/s. If the clay comes to as top in 91 ms, what is the average horizontal force on the clay due to the wall?

42 N

A 10-kg mass, hung by an ideal spring, causes the spring to stretch 2.0cm. What is the spring constant (force constant) for this spring?

49 N/cm

A 100-kg whale swims horizontally to the right at a speed of 6.0 m/s. It suddenly collides directly with a stationary seal of mass 200 kg. The seal grabs onto the whale and holds fast. What is the speed of these two sea creatures just after their collision? You an neglect any drag effects of the water during the collision.

5.0 m/s

Astronaut Jennifer's lifeline to her spaceship comes loose and she finds herself stranded, "floating" 100 m from the mothership. She suddenly throws her 2.00-kg wrench at 20 m/s in a direction away from the ship. If she and her spacesuit have combined mass of 200 kg, how long does it take her to coast back to her spaceship?

500 s

Matthew pulls his little sister Sarah along the horizontal ground in a wagon. He exerts a force on the wagon of 60N at an angle of 37 degrees above the horizontal. If he pulls her a distance of 12.0 m, how much work does Matthew do?

575 J

A 1200-kg ore cart is rolling at 10.8 m/s accross a flat friction-free surface. A crane suddenly drops 858 kg of one vertically into the cart. How fast does the cart move just after being loaded with the ore?

6.30 m/s

A 1200-kg car moving 15.6 m/s suddenly collides with a stationary care of mass 1500 kg. if the two vehicles lock together, what is their combined velocity immediately after the collision?

6.9 m/s

A truck is using a hook to tow a car whose mass is one quarter that of the truck. If the force exerted by the truck on the car is 600 N, then the force exerted by the car on the truck is?

6000 N

What must be your average speed in order to travel 350 km in 5.15 h?

68.0 km/h

If i weight 741N on Earth at a place where g +9.80 m/s2 and 5320N on the surface of another planet, what is the acceleration due to gravity on that planet?

70.4 m/s2

A girl of mass 55 kg throws a ball of mass 0.80 kg against a wall. The ball strikes the wall horizontally with a speed of 25 m/s and it bounces back with the same speed. The ball is in contact with the wall 0.050 s. What is the magnitude of the average force exerted on the wall by the ball?

800 N

Two astronauts of masses 60 kg and 80 kg, are initially right next to each other and at rest in outer space. They suddenly push each other apart. How far has the heavier astronaut moved when the lighter astronaut moved 12m?

9.0 m

An object is moving with constant non-zero acceleration in the positive x direction. The velocity versus time graph of this object is?

A straight line making an angle with the time axis

Which of the following situations is impossible?

An object has constant non-zero velocity and changing acceleration

If velocity of an object is zero at some points, then its acceleration must also be zero at that point.

False

Jill does twice as much work as Jack does and in half the time. Jill's power output is?

Four times Jack's power output.

A ball is thrown downward in the absence or air resistance. After it has been released, which statement(s) concerning its acceleration is correct?(There could be more than one correct choice)

Its acceleration is constant

James and John dive from an overhang into the lake below. James simply drops straight down from the edge. John takes a running start and jumps with an initial horizontal velocity of 25 m/s. Compare the time it takes each to reach the lake below if there is no air resistance.

James and John will reach the surface of the lake at the same time

Inside of a train a ball of weight W is hanging by a light wire at rest from the ceiling. The wire makes an angle ) with the ceiling, as shown in the figure. Which one of the following conditions must be true about the tension T in the wire?

T sin 0 = W

Suppose that a car travelling to the west begins to slow down as it approaches a traffic light. Which of the following statements about its acceleration is correct?

The acceleration is toward the east

A person stands on the edge of a cliff. She throws three identical rocks with the same speed. Rock Xis thrown vertically upward, rock Y is thrown horizontally, and rock Z is thrown vertically downward. If the ground at the vase of the cliff is level, which rock hits the ground with the greatest force?

They all hit the ground with the same speed.

A 10-kg rock and a 20-kg rock are dropped at the same time and experience no significant air resistance. If the 10-kg rock falls with acceleration a, what is the acceleration of the 20-kg rock?

a

While flying horizontal in an airplane, you notice that a string dangling from the overhead luggage compartment hangs at rest at 15 degrees away from the vertical towards the front of the train. Using this observation, you can conclude that the airplane is

accelerating backward

The slope of a velocity versus time graph gives

acceleration

Consider two vectors (a) and (b) shown in the figure. The difference (a) - (b) is best illustrated by

choice (c)

You are trying to cross a river that flows towards the south with a strong currant. You start out in your motorboat on the east bank desiring to reach the west bank directly west from your starting point. You should head your motorboat

in a general northwesterly direction

A railroad collides with and sticks to an identical railroad car that is initially at rest. After the collision, the kinetic energy of the system

is half as much as before

In Einstein's famous equation E=mc2, describing the relationship between matter and energy, E stands for energy, m stands for mass, and c is the speed of light in vaccum. What are the SI units of E?

kg x m2/s2

You are in a train travelling on a horizontal track and notice that a piece of luggage starts to slide directly toward the front of the train. From this observation, you can conclude that this train is

slowing down

If you want to double the kinetic energy of a gas molecule, by what factor must you increase its momentum?

square root of two

A rubber ball bounces off of a wall with an initial speed v and reverses its direction so its speed is v right after the bounce. AS a result of this bounce, which of the following quantities of the ball are conserved? (There could be more than one correct choice).

the kinetic energy of the ball

Two objects of different masses have momentum of equal, non-zero magnitude. Which object has more kinetic energy?

the lighter object

If you pound a feather with a hammer which one feels the greater force

the size of the force is always exactly the same on both of them

Swimmers at a water park have a choice of two frictionless water slides, as shown in the figure. Although both slides drop over the same height h, slide 1 is straight while slide 2 is curved, dropping quickly at first then leveling out. How does the speed of v1 of a swimmer reaching the bottom of slide 1 compare with v2, the speed of a swimmer reaching the end of slide 2?

v1 = v2