Physics Flashcards
Superman must stop a train in 150 m to keep 120 km/h it from hitting a stalled care on the tracks. If the train’s mass is 3.6 × 10⁵ kg, how much force must he exert?
a) 1,333 kN
b) 1,444 kN
c) 1,555 kN
d) 1,666 kN
a) 1,333 kN
A woman stands on a bathroom scale in a motionless elevator. When the elevator begins to move, the scale briefly reads only 0.75 of her regular weight. Calculate the acceleration of the elevator of the elevator and find the direction of acceleration.
a) 2.45 m/s² (upward)
b) 2.45 m/s² (downward)
c) 3.45 m/s² (upward)
d) 3.45 m/s² (downward)
b) 2.45 m/s² (downward)
Two crates, of mass 65 kg and 125 kg, are in contact and at rest on a horizontal surface. a 650-N force is exerted on the 65-kg crate. If the coefficient of kinetic friction is 0.18, calculate the acceleration of the system.
a) 1.66 m/s²
b) 1.77 m/s²
c) 1.88 m/s²
d) 1.99 m/s²
a) 1.66 m/s²
Two crates, of mass 65 kg and 125 kg, are in contact and at rest on a horizontal surface. a 650-N force is exerted on the 65-kg crate. If the coefficient of kinetic friction is 0.18, calculate the force that each crate exerts on the other.
a) 327.63 N
b) 427.63 N
c) 527.63 N
d) 627.63 N
b) 427.63 N
Two crates, of mass 125 kg and 65 kg, are in contact and at rest on a horizontal surface. a 650-N force is exerted on the 120-kg crate. If the coefficient of kinetic friction is 0.18, calculate the force that each crate exerts on the other.
a) 192.37 N
b) 202.37 N
c) 212.37 N
d) 222.37 N
d) 222.37 N
A jet plane traveling 1890 kph pulls out of a dive by moving in an arc of radius 5.20 km. What is the plane’s acceleration?
a) 52 m/s²
b) 53 m/s²
c) 54 m/s²
d) 55 m/s²
b) 53 m/s²
A horizontal force of 310 N is exerted on a 2.0-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.
a) 11.51 m/s²
b) 11.61 m/s²
c) 11.71 m/s²
d) 11.81 m/s²
d) 11.81 m/s²
A 0.55-kg ball, attached to the end of a horizontal cord, is revolved in a circle of radius 1.3 m on a frictionless horizontal surface. If the cord will break when the tension in it exceeds 75 N, what is the maximum speed the ball can have?
a) 11.11 m/s
b) 12.21 m/s
c) 13.31 m/s
d) 14.41 m/s
c) 13.31 m/s
A 0.90-kg body attached to a cord is whirled in a vertical circle of radius 2.50 m. What minimum speed must it have at the top of the circle so as not to depart from the circular path?
a) 3.95 m/s
b) 4.95 m/s
c) 5.95 m/s
d) 6.95 m/s
b) 4.95 m/s
A car at the Indianapolis 500 accelerates uniformly from the pit area, going from rest to 60 kph in a semicircular arc with a radius of 220 m. Determine the tangential acceleration of the car when it is halfway through the arc, assuming constant tangential acceleration.
a) 0.20 m/s²
b) 0.30 m/s²
c) 0.40 m/s²
d) 0.50 m/s²
c) 0.40 m/s²
A car at the Indianapolis 500 accelerates uniformly from the pit area, going from rest to 60 kph in a semicircular arc with a radius of 220 m. Determine the radial acceleration of the car when it is halfway through the arc, assuming constant tangential acceleration.
a) 1.06 m/s²
b) 1.16 m/s²
c) 1.26 m/s²
d) 1.36 m/s²
c) 1.26 m/s²
Two objects attract each other gravitationally with a force of 2.5 × 10⁻¹⁰ N when they are -.25 m apart. Their total mass is 4.00 kg. Find their individual masses.
a) 0.05 kg and 2.94 kg
b) 0.06 kg and 3.94 kg
c) 0.07 kg and 4.94 kg
d) 0.08 kg and 5.94 kg
b) 0.06 kg and 3.94 kg
Calculate the acceleration due to gravity on the Moon, which has a radius of 1.74 × 10⁶ m and mass 7.35 × 10²² kg.
a) 1.32 m/s²
b) 1.42 m/s²
c) 1.52 m/s²
d) 1.62 m/s²
d) 1.62 m/s²
How much work did the movers do (horizontally) pushing a 46.0-kg crate 10.3 m across a rough floor without acceleration, if the effective coefficient of friction was 0.50?
a) 2324 J
b) 2425 J
c) 2526 J
d) 2627 J
a) 2324 J
What is the minimum work needed to push a 950-kg 710 m up along a 9.0°C incline? Ignore friction.
a) 935 kJ
b) 1035 kJ
c) 1135 kJ
d) 1235 kJ
b) 1035 kJ
How much work must be done to stop a 925-kg car traveling at 95 km/h?
a) 211 kJ
b) 222 kJ
c) 311 kJ
d) 322 kJ
d) 322 kJ
By how much does the gravitational potential energy of 54-kg pole vaulter change if her center of mass rises about 4.0 m during the jump?
a) 2009 J
b) 2119 J
c) 2229 J
d) 2339 J
b) 2119 J
A spring as a spring constant k of 88 m/s. How much must this spring be compressed to store 45.0 J of potential energy?
a) 1.01 m
b) 2.01 m
c) 3.01 m
d) 4.01 m
a) 1.01 m
A spring with k = 83 N/m hangs vertically next to a ruler. The end of the spring is next to the 15-cm mark on the ruler. If a 2.5-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?
a) 44.10 cm
b) 54.10 cm
c) 64.10 cm
d) 74.10 cm
d) 74.10 cm
Calculate the force exerted on a rocket when the propelling gases are being expelled at a rate of 1300 kg/s with a speed of 4.5 × 10⁴ m/s.
a) 38,500 kN
b) 48,500 kN
c) 58,500 kN
d) 68,500 kN
c) 58,500 kN
What is the magnitude of the momentum of a 28-g sparrow flying with a speed of 8.4 m/s?
a) 0.14 N
b) 0.24 N
c) 0.34 N
d) 0.44 N
b) 0.24 N
A 0.145-kg baseball pitched at 31.0 m/s is hit on a horizontal line drive straight back at the pitcher at 46.0 m/s. If the contact time between bat and ball is 5 × 10⁻³ s, calculate the force (assumed to be constant) between the ball and bat.
a) 1122 N
b) 2233 N
c) 3344 N
d) 4455 N
b) 2233 N
A 22-g bullet traveling 240 m/s penetrates a 2.0-kg block of wood and emerges going 150 m/s. If the block is stationary on a frictionless surface when hit, how fast does it move after the bullet emerges?
a) 0.73 m/s
b) 0.88 m/s
c) 0.92 m/s
d) 0.99 m/s
d) 0.99 m/s
A 10,000-kg railroad car, A, traveling at a speed of 24.0 m/s strikes an identical car, B, at rest. If the cars lock together as a result of the collision, what is their common speed just afterward?
a) 10 m/s
b) 11 m/s
c) 12 m/s
d) 13 m/s
c) 12 m/s
A ball of mass 0.440 kg moving east with a speed of 3.8 m/s collides head-on with a 0.220-kg ball at rest. If the collision is perfectly elastic, what will be the speed and direction of each ball after the collision?
a) 1.6 m/s (west), 5.4 m/s (east)
b) 1.6 m/s (east), 5.4 m/s (east)
c) 2.7 m/s (west), 4.3 m/s (east)
d) 2.7 m/s (east), 4.3 m/s (east)
b) 1.6 m/s (east), 5.4 m/s (east)
A carousel is initially at rest. At t = 0, it is given a constant angular acceleration ɑ = 0.060 rad/s², which increases its angular velocity for 8.0 s. At t = 8.0 s, determine the angular velocity of the carousel.
a) 0.0075 rad/s
b) 0.48 rad/s
c) 133.33 rad/s
d) 4.8 rad/s
b) 0.48 rad/s
A carousel is initially at rest. At t = 0, it is given a constant angular acceleration ɑ = 0.060 rad/s², which increases its angular velocity for 8.0 s. Determine the linear velocity of a child located 2.5 m from the center.
a) 0.019 m/s
b) 1.2 m/s
c) 12 m/s
d) 3.33 m/s
b) 1.2 m/s
A centrifuge rotor is accelerated for 30 s from rest to 20,000 rpm (revolutions per minute). What is its average angular acceleration?
a) 69.81 rad/s²
b) 66.67 rad/s²
c) 63.66 rad/s²
d) 62.83 rad/s²
a) 69.81 rad/s²
