Physics Chapter 1-5

One half second after starting from rest, a freely falling object will have a speed of about A) 20 m/s. B) 10 m/s. C) 5 m/s. D) 2.5 m/s. E) none of these

C) 5 m/s.

The vertical height attained by a basketball player who achieves a hang time of a full 1 s is A) about 0.8 m. B) about 1 m. C) about 1.2 m. D) about 2.5 m. E) more than 2.5 m.

C) about 1.2 m.

The muzzle velocity of a bullet fired from a new rifle is 100 m/s. Neglecting air resistance, at the end of one second a bullet fired straight up into the air will have traveled a distance of A) (100 - 4.9) m. B) (100 + 4.9) m. C) 100 m. D) 4.9 m. E) none of these

A) (100 - 4.9) m. * Neglecting air resistance but don't forget about gravity which is pulling down .5(9.8)(1^2) .5(G)(1sec^2)

If one object has twice as much mass as another object, it also has twice as much A) inertia. B) velocity. C) acceleration due to gravity. D) volume. E) all of these

A) inertia.

A hockey puck is set in motion across a frozen pond. If ice friction and air resistance are neglected, the force required to keep the puck sliding at constant velocity is A) zero. B) equal to its weight. C) equal to its weight divided by its mass. D) equal to the product of its mass times its weight. Topic: Newton's 1st Law

A) zero. *If ice friction and air resistance are neglected

A 10-kg brick and a 1-kg book are dropped in a vacuum. The force of gravity on the 10-kg brick is A) the same as the force on the 1-kg book. B) 10 times as much. C) one-tenth as much. D) zero.

B) 10 times as much. remember the question is not talking about the acceleration of gravity which is 10m/s^2

A man leans over the edge of a cliff and throws a rock upward at 4.9 m/s. Neglecting air resistance, one second later the rock's speed is A) zero. B) 4.9 m/s. C) 9.8 m/s. D) 14.7 m/s. E) none of the above B) 4.9 m/s.

B) 4.9 m/s.

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

B) is zero.

A skydiver jumps from a high-flying plane. As her velocity of fall increases, her acceleration... A) Increase B) Decrease C) Remain unchanged

B. Decrease as she falls, air resistance increases causing the acceleration to decrease.

An apple at rest weighs 1 N. The net force on the apple when it is in free fall is A) 0 N. B) 0.1 N. C) 1 N. D) 9.8 N. E) none of these

C) 1 N.

A jumbo jet has a mass of 100,000 kg. The thrust for each of its four engines is 50,000 N. What is the jet's acceleration in meters per second per second when taking off? A) 0.25 B) 1 C) 2 D) 4 E) none of these

C) 2 a = f/m a = (50,000 * 4)/100,000 a = 200,000/100,000 a = 2

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

C) 250 m. d = .5at^2 d = .5(20)(5^2) d = (10)(25) d = 250

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 brakes were applied was A) 1.2 m/s. B) 15 m/s. C) 30 m/s. D) 45 m/s. E) none of these

C) 30 m/s. S = at S = 10000/2000 * 6

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) 100 m B) 200 m C) 300 m D) 400 m E) none of these C) 300 m

D = speed * time speed = 20+40/2 = 30 D = 30 * 10 = 300 m

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 these E) none of these

D) all of these

Your friend says that the heavyweight champion of the world cannot exert a force of 50 N on a piece of tissue paper with his best punch. The tissue paper is held in midair - no wall, no tricks. You A) agree that it can't be done. B) have reservations about this assertion. C) disagree, for a good punch easily delivers this much force.

A) agree that it can't be done.

If a car increases its velocity from zero to 60 km/h in 10 seconds, its acceleration is A) 3 km/h/s. B) 6 km/h/s. C) 10 km/h/s. D) 60 km/h/s. E) 600 km/h/s.

B) 6 km/h/s. 60/10 = 6 60km/h divided by 10 seconds = 6 km/h/s

A man leans over the edge of a cliff and throws a rock upward at 4.9 m/s. How far below the level from which it was thrown is the rock 2 seconds later? A) 4.9 m B) 9.8 m C) 14.7 m D) 19.6 m B) 9.8 m

B) 9.8 m

The mass of a pet turtle that weighs 10 N is A) about 1000 kg B) about 1 kg C) about 10 kg about 100 kg

B) about 1 kg

A ball is thrown 125 meters upward and then falls the same distance back to Earth. Neglecting air resistance, its total time in the air is A) about 5 seconds. B) about 10 seconds. C) about 15 seconds. D) more than 20 seconds.

B) about 10 seconds.

The maximum acceleration of a car while towing a second car twice its mass, compared to its acceleration with no car in tow, is A) one half. B) one third. C) one fourth. D) the same. E) none of these

B) one third.

An apple weighs 1 N. When held at rest above your head, the net force on the apple is A) 0 N. B) 0.1 N. C) 1 N. D) 9.8 N. E) none of these

A) 0 N.

If a projectile is fired straight up at a speed of 10 m/s, the time it takes to reach the top of its path is about A) 1 second. B) 2 seconds. C) 10 seconds. D) not enough information to estimate

A) 1 second. accelerating downward 10m/s. At 1 second it would be at 0m/s

A 10-kilogram block is pushed across a horizontal surface with a horizontal force of 20 N against a friction force of 10 N. The acceleration of the block in meters per second per second is A) 1. B) 2. C) 5. D) 10. E) none of these

A) 1. 20 N - 10 N Friction = 10 N 10 kg / 10 N = 1

A pot falls from a ledge and hits the ground 45 m below. The speed with which it hits the ground is A) about 30 m/s. B) about 60 m/s. C) about 120 m/s. D) more than 120 m/s.

A) about 30 m/s. 45 meter = .5(10)(t^2) 45 meter = 5(t^2) 9 meters = t^2

A ball is thrown upwards. Neglecting air resistance, what initial upward speed does the ball need to remain in the air for a total time of 10 seconds? A) about 50 m/s B) about 60 m/s C) about 80 m/s D) about 100 m/s E) about 110 m/s

A) about 50 m/s Remember is spends 1/2 time coming down

A ball is thrown upwards. Neglecting air resistance, what initial upward speed does the ball need to remain in the air for a total time of 10 seconds? A) about 50 m/s B) about 60 m/s C) about 80 m/s D) about 100 m/s E) about 110 m/s

A) about 50 m/s Up 5 seconds down 5 seconds

Strange as it may seem, it is just as hard to accelerate a car on a level surface on the moon as it is here on the Earth. This is because A) the mass of the car is independent of gravity. B) the weight of the car is independent of gravity. C) Nonsense! A car is much more easily accelerated on the moon than on the Earth. A) the mass of the car is independent of gravity.

A) the mass of the car is independent of gravity.

While an object near the Earth's surface is in free fall, its A) velocity increases. B) acceleration increases. C) mass increases. D) mass decreases.

A) velocity increases.

The force required to maintain an object at a constant velocity in free space is equal to A) zero. B) the mass of the object. C) the weight of the object. D) the force required to stop it. E) none of these

A) zero.

An apple falls from a tree and hits the ground 5 meters below. It hits the ground with a speed of about A) 5 m/s. B) 10 m/s. C) 15 m/s. D) 20 m/s. E) not enough information given to estimate

B) 10 m/s.

A car traveling at 22 m/s comes to an abrupt halt in 0.1 second when it hits a tree. What is the deceleration in meters per second per second of the car? A) 110 B) 220 C) 800 D) 880 E) can't be solved without the mass of the car

B) 220 a = v/t a = 22/.1 a = 220

A girl 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 in meters per second per second? A) 0.3 B) 3.0 C) 10 D) 30 E) 300

B) 3.0 Acceleration = Force / Mass (a = F / m) a = 30/10

Two people, one twice as massive as the other, attempt a tug-of-war with 12 meters of massless rope on frictionless ice. After a brief time, they meet. The heavier person slides a distance of A) 3 m. B) 4 m. C) 6 m. D) 0 m. B) 4 m.

B) 4 m.

A 300-kg bear grasping a vertical tree slides down at 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. Since the bear is sliding down at a constant velocity, its acceleration is 0. So, the sum of the forces is 0. Thus: Friction (upward) + Weight (downward) = 0 F - mg = 0 F = mg = (300 kg)(10 m/s^2) = 3000 N

If a rocket initially at rest accelerates at a rate of 50 m/s2 for one minute, its speed will be A) 50 m/s. B) 500 m/s. C) 3000 m/s. D) 3600 m/s.

C) 3000 m/s. 50 * 60 = 3000 50m/s^2 * 60 seconds = 3000

It takes 6 seconds for a stone to fall to the bottom of a mine shaft. How deep is the shaft? A) about 60 m B) about 120 m C) about 180 m D) more than 200 m

C) about 180 m * d = .5at^2 distance = .5(10)(6^2) distance = 5(36) Distance = 180

A car accelerates at 2 meters/s/s. Assuming the car starts from rest, how far will it travel in 10 s? A) 2 m B) 10 m C) 40 m D) 100 m E) 200 m

D) 100m * d = .5at^2 d = .5(2)(10^2) d = (1)(100) d = 100

A man leans over the edge of a cliff and throws a rock upward at 4.9 m/s. Neglecting air resistance, two seconds later the rock's speed is A) zero. B) 4.9 m/s. C) 9.8 m/s. D) 14.7 m/s. E) none of the above

D) 14.7 m/s.

A car accelerates from rest for 5 seconds until it reaches a speed of 20 m/s. What is the car's acceleration in meters per second per second? A) 1 B) 2 C) 3 D) 4 E) 5

D) 4

A vehicle that weighs 4000 N on the surface of the Earth is travelling in outer space at a speed of 200 m/s. The smallest constant force that must be applied to stop it in 20 seconds is A) 20 N. B) 40 N. C) 400 N. D) 4000 N. E) more than 4000 N.

D) 4000 N. If vehicle has weight 4000N on earth , mass = 400kg If vehicle is travelling at 200m/s, what acceleration is required to bring it to rest in 20s? v = u +at 0 = 200 + a*20 a = 200/-20 a = -10m/s² Minus sign confirms that the acceleration is opposite to direction of travel - that is it is slowing vehicle down Equation: F = m*a F = 400*10 F = 4000N - answer 2 years ago

A 10-kilogram block with an initial velocity of 10 m/s slides 10 meters across a horizontal surface and comes to rest. It takes the block 2 seconds to stop. The stopping force acting on the block is about A) 5 N. B) 10 N. C) 25 N. D) 50 N. E) none of these

D) 50 N. You're trying to find a force, and we know that Force=mass*acceleration, so you need the acceleration. Acceleration = (Final Velocity - Initial Velocity)/Time Final Velocity = 0 m/s (it stops) Initial Velocity = 10 m/s Time = 2 seconds Acceleration = (0 - 10)/2 = -5m/s^2 Now to find the force... Mass = 10kg Force = 10kg * -5m/s^2 = -50N

While a car travels around a circular track at a constant speed, its A) acceleration is zero. B) velocity is zero. C) inertia is zero. D) none of the above

D) none of the above

A vehicle that weights 400 N on the surface of the Earth is traveling in outer space at a speed of 400 m/s . It can be stopped by applying a constant force of 20 N for A) 2 seconds. B) 4 seconds. C) 80 seconds. D) 400 seconds. E) 800 seconds.

E) 800 seconds. Calculate the mass of the object: F = ma m = F/a = 400 N / 9.81 m/s/s m = 40.77 kg -------------------------- F = ma a = F/m = 20N / 40.77 kg a = 0.490 m/s/s v = at t = v/a = 400/0.490 = 800 seconds (rounded off). ------------

The brakes of a speeding truck are slammed on and it skids to a stop. If the truck were heavily loaded so that it had twice the total mass, the skidding distance would be A) 1/2 as far. B) 1 1/2 times as far. C) 2 times as far. D) 4 times as far. E) the same.

E) the same distance. Loading a truck with twice the total mass (weight), causes the force exerted by the tires on the road to double (2x). Therefore the force of friction (causing the truck to decelerate) also doubles (2x). So: force = mass x acceleration, force = 2x; mass = 2x; acceleration = the same

A rock is thrown vertically into the air. At the very top of its trajectory the net force on the rock is? a. less than its weight b. more than its weight c. equal to its weight d. zero

c. equal to its weight