PH 101 Final
To seven significant figures, the mass of a proton is 1.672623×10^−27 kg. Which of the following choices demonstrates correct rounding? 1.672×10^−27 kg 1.67×10^−27 kg 1.67263×10^−27 kg
1.67×10^−27 kg
What is the percent uncertainty in the measurement 3.26±0.25m?
7.7%
Two railroad cars, each of mass 74000 kg and traveling 65 km/h in opposite directions, collide head-on and come to rest. How much thermal energy is produced in this collision?
E = 24 MJ
Calculate the period of a satellite orbiting the Moon, 99 km above the Moon's surface. Ignore effects of the Earth. The radius of the Moon is 1740 km.
T = 7080 s
A 8700-kg boxcar traveling at 16 m/s strikes a second boxcar at rest. The two stick together and move off with a speed of 7.5 m/s . What is the mass of the second car?
m2 = 9900 kg
What is the magnitude of the momentum of a 34 g sparrow flying with a speed of 3.5 m/s ?
p = 0.12 kg⋅m/s
To calculate the change in kinetic energy, you must know the force as a function of _______. The work done by the force causes the kinetic energy change. acceleration work position potential energy
position
A 66-kg skier starts from rest at the top of a 1200-m-long trail which drops a total of 290 m from top to bottom. At the bottom, the skier is moving 11 m/s. How much energy was dissipated by friction?
Efr = 180 kJ
A 21.0-kg child descends a slide 2.30 m high and reaches the bottom with a speed of 1.40 m/s. How much thermal energy due to friction was generated in this process?
Efr = 453 J
A baseball (m=145g) traveling 40 m/s moves a fielder's glove backward 27 cm when the ball is caught. What was the average force exerted by the ball on the glove?
F on glove = 430 N
Calculate the force of Earth's gravity on a spacecraft 2.00 Earth radii above the Earth's surface if its mass is 1850 kg
FG = 2010 N
Arlene is to walk across a "high wire" strung horizontally between two buildings 15.0 m apart. The sag in the rope when she is at the midpoint is 10.0 degrees. If her mass is 51.0 kg , what is the tension in the rope at this point?
FT = 1440 N
A pump is to lift 21.0 kg of water per minute through a height of 3.70 m . What minimum output rating (watts) must the pump motor have?
P = 12.7 W
You buy a plastic dart gun, and being a clever physics student you decide to do a quick calculation to find its maximum horizontal range. You shoot the gun straight up, and it takes 3.6 s for the dart to land back at the barrel. What is the maximum horizontal range of your gun?
R = 32 m
How much work is required to stop an electron (m=9.11×10^−31 kg) which is moving with a speed of 1.30×10^6 m/s?
W = −7.70×10^−19 J
What is the minimum work needed to push a 950 -kg car 700 m up along a 8.0 ∘ incline? Ignore friction.
WP = 9.1×10^5 J
Time intervals measured with a stopwatch typically have an uncertainty of about 0.2 s, due to human reaction time at the start and stop moments. a) What is the percent uncertainty of a handtimed measurement of 5 s ? b) What is the percent uncertainty of a handtimed measurement of 50 s ? c) What is the percent uncertainty of a handtimed measurement of 4 min ?
a) 4% b) 0.4% c) 8×10^−2%
a) Find the components of the vector A⃗ with length a = 1.00 and angle α=20.0 ∘ with respect to the x axis b) Find the components of the vector B⃗ with length b = 1.00 and angle β=20.0 ∘ with respect to the x axis c) Find the components of the vector C⃗ with length c = 1.00 and angle ϕ= 35.0 degrees *A on x-axis in quadrant I, B on x-axis in quadrant II, C on y-axis with hypotenuse facing upwards in quadrant II
a) A⃗ = 0.940, 0.342 b) B⃗ = 0.940, 0.342 c) C⃗ = -0.574, 0.819
A 25.5-kg box is released on a 27 ∘ incline and accelerates down the incline at 0.22 m/s^2. a) Find the friction force impeding its motion. b) Determine the coefficient of kinetic friction.
a) Ffr = 110 N b) μk = 0.48
Two forces, F⃗ 1 and F⃗ 2, act at a point, as shown in the picture. (Figure 1) F⃗ 1 has a magnitude of 9.80 N and is directed at an angle of α = 61.0 ∘ above the negative x axis in the second quadrant. F⃗ 2 has a magnitude of 6.40 N and is directed at an angle of β = 53.7 ∘ below the negative x axis in the third quadrant. a) What is the x component Fx of the resultant force? b) What is the y component Fy of the resultant force? c) What is the magnitude F of the resultant force? d) What is the angle γ that the resultant force forms with the negative x axis? In this problem, assume that positive angles are measured clockwise from the negative x axis.
a) Fx = -8.54 N b) Fy = 3.41 N c) F = 9.20 N d) γ = 21.8 degrees
Consider two objects (Object 1 and Object 2) moving in the same direction on a frictionless surface. Object 1 moves with speed v1=v and has mass m1=2m. Object 2 moves with speed v2=2√v and has mass m2=m. a) Which object has the larger magnitude of its momentum? Object 1 has the greater magnitude of its momentum. Object 2 has the greater magnitude of its momentum. Both objects have the same magnitude of their momenta. b) Which object has the larger kinetic energy? Object 1 has the greater kinetic energy. Object 2 has the greater kinetic energy. The objects have the same kinetic energy.
a) object 1 b) same
A 150-g baseball is dropped from a tree 11.0 m above the ground. a) With what speed would it hit the ground if air resistance could be ignored b) If it actually hits the ground with a speed of 9.00 m/s , what is the magnitude of the average force of air resistance exerted on it?
a) v = 14.7 m/s b) Ffr = 0.918 N
A stone is thrown vertically upward with a speed of 29.0 m/s . a) How fast is it moving when it is at a height of 14.0 m ? b) How much time is required to reach this height?
a) v14.0m = 23.8 m/s b) t1, t2 = 0.530, 5.39 s
An object is hanging by a string from your rearview mirror. a) While you are decelerating at a constant rate from 30 m/s to rest in 6.7 s , what angle does the string make with the vertical? b) Is the angle toward the windshield or away from it?
a) θ = 25 degrees b) The angle is toward the windshield
A force of 37.0 N is required to start a 5.0-kg box moving across a horizontal concrete floor. a) What is the coefficient of static friction between the box and the floor? b) If the 37.0-N force continues, the box accelerates at 0.50 m/s2 . What is the coefficient of kinetic friction?
a) μs = 0.76 b) μk = 0.70
Rather than ascribing the increased kinetic energy of the stone to the work of gravity, we now (when using potential energy rather than work-energy) say that the increased kinetic energy comes from the ______ of the _______ energy. work / potential force / kinetic change / potential
change / potential
To illustrate the work-energy concept, consider the case of a stone falling from xi to xf under the influence of gravity. Using the work-energy concept, we say that work is done by the gravitational _____, resulting in an increase of the ______ energy of the stone. force / kinetic potential energy / potential force / potential potential energy / kinetic
force / kinetic
Calculate the acceleration due to gravity on the Moon. The Moon's radius is 1.74×10^6 m and its mass is 7.35×10^22 kg.
gMoon = 1.62 m/s^2
A ball thrown horizontally at 12.9 m/s from the roof of a building lands 20.4 m from the base of the building. How tall is the building?
h = 12.3 m
A stone is dropped from the top of a cliff. It is seen to hit the ground below after 2.57 s . How high is the cliff?
h = 32.4 m
If the kinetic energy of a particle is doubled, by what factor has its speed increased?
the speed is multiplied by a factor = 1.4
A rolling ball moves from x1 = 8.6 cm to x2 = -4.8 cm during the time from t1 = 3.1 s to t2 = 6.8 s . What is its average velocity over this time interval?
v = -3.6 cm/s
A horizontal force of 300 N is exerted on a 1.5-kg ball as it rotates (at arm's length) uniformly in a horizontal circle of radius 0.90 m. Calculate the speed of the ball.
v = 13 m/s
A 0.75-kg ball, attached to the end of a horizontal cord, is rotated in a circle of radius 2.1 m on a frictionless horizontal surface. If the cord will break when the tension in it exceeds 90 N , what is the maximum speed the ball can have?
v = 16 m/s
In coming to a stop, a car leaves skid marks 76 m long on the highway. Assuming a deceleration of 3.50 m/s^2 , estimate the speed of the car just before braking.
v = 23 m/s
What is the maximum speed with which a 1200-kg car can round a turn of radius 95.0 m on a flat road if the coefficient of static friction between tires and road is 0.60? Is this result independent of the mass of the car?
v = 24 m/s; yes
At room temperature, an oxygen molecule, with mass of 5.31×10^−26 kg, typically has a kinetic energy of about 6.21×10^−21 J. How fast is it moving?
v = 484 m/s
A novice skier, starting from rest, slides down an icy frictionless 12 degree incline whose vertical height is 180 m. How fast is she going when she reaches the bottom?
v = 59 m/s
What must be your car's average speed in order to travel 232 km in 3.22 h ?
v = 72.0 km/h
Police investigators, examining the scene of an accident involving two cars, measure 66-m-long skid marks of one of the cars, which nearly came to a stop before colliding. The coefficient of kinetic friction between rubber and the pavement is about 0.78. Estimate the initial speed of that car assuming a level road.
v0 = 32 m/s
An 93-g arrow is fired from a bow whose string exerts an average force of 130 N on the arrow over a distance of 73 cm . What is the speed of the arrow as it leaves the bow?
v2 = 45 m/s
A ball is thrown horizontally from the roof of a building 8.0 m tall and lands 9.9 m from the base. What was the ball's initial speed?
vx = 7.7 m/s
A spring with k = 57 N/m hangs vertically next to a ruler. The end of the spring is next to the 19-cm mark on the rule. If a 3.0-kg mass is now attached to the end of the spring, and the mass is allowed to fall, where will the end of the spring line up with the ruler marks when the mass is at its lowest position?
x = 120 cm
You are given a vector in the xy plane that has a magnitude of 90.0 units and a y component of -60.0 units. What are the two possibilities for its x component?
x1, x2 = 67.1, -67.1 units
A flatbed truck is carrying a heavy crate. The coefficient of static friction between the crate and the bed of the truck is 0.69. What is the maximum rate at which the driver can decelerate and still avoid having the crate slide against the cab of the truck?
|a| = 6.8 m/s^2
By how much does the gravitational potential energy of a 59-kg pole vaulter change if her center of mass rises about 4.0 m during the jump?
ΔPEG = 2300 J
A constant friction force of 19 N acts on a 57-kg skier for 16 s on level snow.What is the skier's change in velocity?
Δv = -5.3 m/s
A tiger leaps horizontally from a 5.7 m -high rock with a speed of 3.7 m/s . How far from the base of the rock will she land?
Δx = 4.0 m
The coefficient of static friction between hard rubber and normal street pavement is about 0.82. On how steep a hill (maximum angle) can you leave a car parked?
θ = 39 degrees
A skateboarder, with an initial speed of 4.0 m/s , rolls virtually friction free down a straight incline of length 20 m in 3.3 s. At what angle θ is the incline oriented above the horizontal?
θ = 7.3 degrees
To eight significant figures, Avogadro's constant is 6.0221367×10^23 mol−1. Which of the following choices demonstrates correct rounding? 6.022×10^23 mol−1 6.0×10^23 mol−1 6.02214×10^23 mol−1
6.022×10^23 mol−1 6.0×10^23 mol−1 6.02214×10^23 mol−1
A 0.145-kg baseball pitched at 31.5 m/s is hit on a horizontal line drive straight back at the pitcher at 44.0 m/s . If the contact time between bat and ball is 5.30×10^−3 s , calculate the magnitude of the force (assumed to be constant) exerted on the ball by the bat.
F = 2070 N
Determine the mass of the Earth from the known period and distance of the Moon.
MEarth = 5.98×10^24 kg
Given that the acceleration of gravity at the surface of Mars is 0.38 of what it is on Earth, and that Mars' radius is 3400 km, determine the mass of Mars.
MMars = 6.5×10^23 kg
Neptune is an average distance of 4.5×10^9 km from the Sun. Estimate the length of the Neptunian year using the fact that the Earth is 1.50×10^8 km from the Sun on average.
TNeptune = 164 years
A car slows down from 29 m/s to rest in a distance of 79 m . What was its acceleration, assumed constant?
a = -5.3 m/s^2
A sports car accelerates from rest to 97 km/h in 5.5 s . What is its average acceleration in m/s^2.
a = 4.9 m/s^2
A 26-kg chandelier hangs from a ceiling on a vertical 4.0-m-long wire. a) What horizontal force would be necessary to displace its position 0.16 m to one side? b) What will be the tension in the wire?
a) FH = 10 N b) FT = 260 N
A ball of mass 0.245 kg that is moving with a speed of 5.5 m/s collides head-on and elastically with another ball initially at rest. Immediately after the collision, the incoming ball bounces backward with a speed of 3.2 m/s . a) Calculate the velocity of the target ball after the collision. b) Calculate the mass of the target ball
a) v = 2.3 m/s b) m = 0.93 kg
A shot-putter throws the "shot" (mass = 7.3 kg) with an initial speed of 15.0 m/s at a 36.0 ∘ angle to the horizontal. Calculate the horizontal distance traveled by the shot if it leaves the athlete's hand at a height of 2.15 m above the ground.
d = 24.5 m
Chris jumps off a bridge with a bungee cord (a heavy stretchable cord) tied around his ankle. He falls for 15 m before the bungee cord begins to stretch. Chris's mass is 78 kg and we assume the cord obeys Hooke's law, F=−kx, with 54 N/m . If we neglect air resistance, estimate what distance d below the bridge Chris's foot will be before coming to a stop. Ignore the mass of the cord (not realistic, however) and treat Chris as a particle.
d = 54 m
If the speed of a particle is decreased by a factor of three, by what factor does its kinetic energy change?
the kinetic energy is multiplied by a factor = 0.11
An object will have constant acceleration if there are no forces at all acting on it. the net force acting on it is zero. the net force acting on it is constant in magnitude and direction. there is only one force acting on it
the net force acting on it is constant in magnitude and direction.
An object cannot remain at rest unless there are no forces at all acting on it. the net force acting on it is zero. the net force acting on it is constant. there is only one force acting on it.
the net force acting on it is zero.
If a car is moving to the left with constant velocity, one can conclude that there must be no forces applied to the car. the net force applied to the car is directed to the left. the net force applied to the car is zero. there is exactly one force applied to the car
the net force applied to the car is zero.
A 920-kg sports car collides into the rear end of a 2200-kg SUV stopped at a red light. The bumpers lock, the brakes are locked, and the two cars skid forward 2.8 m before stopping. The police officer, estimating the coefficient of kinetic friction between tires and road to be 0.80, calculates the speed of the sports car at impact. What was the speed sports car at impact?
v = 22 m/s
A sled is initially given a shove up a frictionless 33.0 degree incline. It reaches a maximum vertical height 1.15 m higher than where it started at the bottom. What was its initial speed?
v initial = 4.75 m/s
Two billiard balls of equal mass undergo a perfectly elastic head-on collision. If one ball's initial speed was 1.60 m/s , and the other's was 2.40 m/s in the opposite direction, what will be their speeds after the collision?
v1, v2 = 2.40, 1.60 m/s
An atomic nucleus initially moving at 345 m/s emits an alpha particle in the direction of its velocity, and the remaining nucleus slows to 280 m/s . If the alpha particle has a mass of 4.0 u and the original nucleus has a mass of 222 u, what speed does the alpha particle have when it is emitted?
v′α = 3900 m/s
The distance between a carbon atom (m = 12 u) and an oxygen atom (m = 16 u) in the CO molecule is 1.13 × 10^-10 m. How far from the carbon atom is the center of mass of the molecule?
xCM = 6.5×10^−11 m
What average force is required to stop a 1900 kg car in 9.0 s if the car is traveling at 100 km/h ?
F = -5900 N
How much work did the movers do (horizontally) pushing a 50.0-kg crate 10.3 m across a rough floor without acceleration, if the effective coefficient of friction was 0.40?
W = 2000 J
If it requires 4.0 J of work to stretch a particular spring by 2.0 cm from its equilibrium length, how much more work will be required to stretch it an additional 4.0 cm?
W = 32 J
A box of mass 7.0 kg is accelerated from rest across a floor at a rate of 5.0 m/s^2 for 6.0 s . Find the net work done on the box.
W = 3200 J
If you are driving 85 km/h along a straight road and you look to the side for 2.7 s , how far do you travel during this inattentive period?
d = 64 m
A falling stone takes Δt = 0.38 s to travel past a window 2.2 m tall. From what height above the top of the window did the stone fall?
h = 0.79 m
This process happens in such a way that total mechanical energy, equal to the ______ of the kinetic and potential energies, is _______. sum / conserved sum / zero sum / not conserved difference / conserved
sum / conserved
A skier traveling 11.0 m/s reaches the foot of a steady upward 18 degree incline and glides 15 m up along this slope before coming to rest. What was the average coefficient of friction?
μ = 0.11
How large must the coefficient of static friction be between the tires and the road if a car is to round a level curve of radius 130 m at a speed of 119 km/h ?
μ = 0.86
If a curve with a radius of 98 m is properly banked for a car traveling 73 km/h , what must be the coefficient of static friction for a car not to skid when traveling at 96 km/h ?
μmin = 0.24
What force is needed to accelerate a sled (total mass = 60 kg ) at 1.2 m/s2 on horizontal frictionless ice?
F = 72 N
Block 1, of mass m1 = 4.90 kg , moves along a frictionless air track with speed v1 = 19.0 m/s . It collides with block 2, of mass m2 = 57.0 kg , which was initially at rest. The blocks stick together after the collision. a) Find the magnitude pi of the total initial momentum of the two-block system. b) Find vf, the magnitude of the final velocity of the two-block system. c) What is the change ΔK=Kfinal−Kinitial in the two-block system's kinetic energy due to the collision?
a) pi = 93.1 kg⋅m/s b) vf = 1.50 m/s c) ΔK = -814 J
At an accident scene on a level road, investigators measure a car's skid mark to be 79 m long. It was a rainy day and the coefficient of friction was estimated to be 0.35. a) Use these data to determine the speed of the car when the driver slammed on (and locked) the brakes. b) Why does the car's mass not matter? Since the change in kinetic energy and the work done by friction do not depend on mass. Since both the change in kinetic energy and the work done by friction are proportional to the mass. The mass cancels out of the equation. Since the work done by friction does not depend on mass.
a) v = 23 m/s b) Since both the change in kinetic energy and the work done by friction are proportional to the mass. The mass cancels out of the equation.
A 67-kg trampoline artist jumps upward from the top of a platform with a vertical speed of 4 m/s . a) How fast is he going as he lands on the trampoline, 2 m below? b) If the trampoline behaves like a spring of spring constant 7.1×104 N/m , how far does he depress it?
a) v = 7.4 m/s b) y = 0.24 m
A ball of mass 0.638 kg moving east (+x direction) with a speed of 3.70 m/s collides head-on with a 0.319 kg ball at rest. Assume that the collision is perfectly elastic. a) What is be the speed of the 0.638-kg ball after the collision? b) What is be the direction of the velocity of the 0.638-kg ball after the collision? c) What is the speed of the 0.319-kg ball after the collision? d) What is the direction of the velocity of 0.319-kg ball after the collision?
a) v1 = 1.23 m/s b) to the east c) v2 = 4.93 m/s d) to the east
An airplane is traveling 835 km/h in a direction 41.5 ∘ west of north a) Find the components of the velocity vector in the northerly and westerly directions. b) How far north and how far west has the plane traveled after 2.40 h ?
a) vnorth, vwest = 625, 553 km/h b) Δdnorth, Δdwest = 1500, 1330 km
A rescue plane wants to drop supplies to isolated mountain climbers on a rocky ridge 235 m below. a) If the plane is traveling horizontally with a speed of 183 km/h (50.8 m/s ), how far in advance of the recipients (horizontal distance) must the goods be dropped? b) Suppose, instead, that the plane releases the supplies a horizontal distance of 425 m in advance of the mountain climbers. What vertical velocity (up or down) should the supplies be given so that they arrive precisely at the climbers' position? c) With what speed do the supplies land in the latter case?
a) x = 352 m b) vy0 = 12.9 m/s c) v = 85.8 m/s
A baseball is hit almost straight up into the air with a speed of 23 m/s . a) Estimate how high it goes. b) Estimate how long it is in the air.
a) ymax = 27.0 m b) t = 4.69 s
The work-energy theorem states that a force acting on a particle as it moves over a ______ changes the ______ energy of the particle if the force has a component parallel to the motion. distance / potential distance / kinetic vertical displacement / potential none of the above
distance / kinetic
A light plane must reach a speed of 38 m/s for takeoff. How long a runway is needed if the (constant) acceleration is 3.0 m/s^2 ?
dmin = 240 m
Calculate the speed of a satellite moving in a stable circular orbit about the Earth at a height of 4840 km .
v = 5960 m/s
A child in a boat throws a 5.85-kg package out horizontally with a speed of 10.0 m/s. The mass of the child is 21.6 kg and the mass of the boat is 34.0 kg .Calculate the velocity of the boat immediately after, assuming it was initially at rest.
v′A = -1.05 m/s
An atomic nucleus at rest decays radioactively into an alpha particle and a different nucleus. What will be the speed of this recoiling nucleus if the speed of the alpha particle is 3.0×10^5 m/s ? Assume the recoiling nucleus has a mass 57 times greater than that of the alpha particle.
v′nucleus = 5300 m/s
A spring has a spring stiffness constant k of 80.0 N/m How much must this spring be compressed to store 30.0 J of potential energy?
x = 0.866 m
Two blocks of ice, one four times as heavy as the other, are at rest on a frozen lake. A person pushes each block the same distance d. Ignore friction and assume that an equal force F⃗ is exerted on each block. a) Which of the following statements is true about the kinetic energy of the heavier block after the push? It is smaller than the kinetic energy of the lighter block. It is equal to the kinetic energy of the lighter block. It is larger than the kinetic energy of the lighter block. It cannot be determined without knowing the force and the mass of each block. b) Compared to the speed of the heavier block, what is the speed of the light block after both blocks move the same distance d? one quarter as fast half as fast the same speed twice as fast four times as fast c) Now assume that both blocks have the same speed after being pushed with the same force F⃗ . What can be said about the distances the two blocks are pushed? The heavy block must be pushed 16 times farther than the light block. The heavy block must be pushed 4 times farther than the light block. The heavy block must be pushed 2 times farther than the light block. The heavy block must be pushed the same distance as the light block. The heavy block must be pushed half as far as the light block.
a) It is equal to the kinetic energy of the lighter block. b) twice as fast c) The heavy block must be pushed 4 times farther than the light block.
a) If Vx = 9.9 units and Vy = -6.6 units, determine the magnitude of V⃗ . b) Determine the direction of V⃗ .
a) V = 11.9 units b) θ = 33.7 degrees below the positive x-axis
Vector V⃗ 1 is 6.1 units long and points along the negative x axis. Vector V⃗ 2 is 8.7 units long and points at 45 ∘ to the positive x axis. a) What are the x and y components of vector V⃗ 1? b) What are the x and y components of vector V⃗ 2? c) Determine the magnitude of the sum V⃗ 1+V⃗ 2. d) Determine the angle of the sum V⃗ 1+V⃗ 2.
a) V1x, V1y = -6.1, 0 units b) V2x, V2y = 6.2, 6.2 units c) ∣∣V⃗ 1+V⃗ 2∣∣ = 6.2 units d) θ = 90 degrees counterclockwise from the positive x-axis
A 13.0 kg bucket is lowered vertically by a rope in which there is 188 N of tension at a given instant. a) Determine the magnitude of the acceleration of the bucket. b) Is it up or down?
a) a = 4.7 m/s^2 b) Up
A number written in scientific notation has the form a×10k, where 1≤a<10 and k is an integer, that is, k is one of ...−3,−2,−1,0,1,2,3.... a) Determine the values of a and k when 299,790,000 is written in scientific notation. b) Determine the values of a and k when 0.51 is written in scientific notation. c) Now consider the expression 4.0×10^3+4×10^2. Determine the values of a and k when the value of this expression is written in scientific notation. d) Finally, consider the expression [(6.67×10^−11)(5.97×10^24)](6.38×10^6)^2. Determine the values of a and k when the value of this expression is written in scientific notation.
a) a, k = 2.9979, 8 b) a, k = 5.1, -1 c) a, k = 4.4, 3 d) a, k = 9.78, 0
A child sitting 1.30 m from the center of a merry-go-round moves with a speed of 1.35 m/s . a) Calculate the centripetal acceleration of the child. b) Calculate the net horizontal force exerted on the child. (mass = 25.5 kg )
a) aR = 1.40 m/s^2 b) FR = 35.7 N
You are driving home from school steadily at 96 km/h for 190 km . It then begins to rain and you slow to 61 km/h instantly. You arrive home after driving 5.0 hours. a) How far is your hometown from school? b) What was your average speed?
a) d = 370 km b) v = 75 km/h
A projectile is fired with an initial speed of 37.5 m/s at an angle of 44.8 ∘ above the horizontal on a long flat firing range. a) Determine the maximum height reached by the projectile. b) Determine the total time in the air. c) Determine the total horizontal distance covered (that is, the range). d) Determine the speed of the projectile 1.10 s after firing.
a) hmax = 35.6 m b) ttotal = 5.39 s c) dtotal = 143 m d) v = 30.9 m/s
At the surface of a certain planet, the gravitational acceleration g has a magnitude of 21.0 m/s^2 . A 30.0-kg brass ball is transported to this planet. a) What is the mass of the brass ball on the Earth and on the planet? b) What is the weight of the brass ball on the Earth and on the planet?
a) mEarth, mPlanet = 30.0, 30.0 kg b) wEarth, wPlanet = 294, 630 N
At what distance from the Earth will a spacecraft traveling directly from the Earth to the Moon experience zero net force because the Earth and Moon pull with equal and opposite forces?
r = 3.46×10^8 m
The asteroid Icarus, though only a few hundred meters across, orbits the Sun like the planets. Its period is 410 d. What is its mean distance from the Sun?
rIcarus = 1.6×10^11 m
A football is kicked at ground level with a speed of 17.1 m/s at an angle of 32.9 ∘ to the horizontal. How much later does it hit the ground?
t = 1.90 s
A car traveling 98 km/h is 290 m behind a truck traveling 88 km/h . How long will it take the car to reach the truck?
t = 100 s
How long will it take a 3750-W motor to lift a 360-kg piano to a sixth-story window 18.0 m above?
t = 16.9 s