Packet # 1 – Mechanics



Packet # 1 – Mechanics

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Speed

1. What is the average speed, in m/s, of a skier who travels 1.2 km downhill in 60 s?

2. Darnley drives from Waterboro to Felixburg, a distance of 325 km, in 5 hrs. What is his average speed in m/s?

3. A bullet fired from a rifle travels 4.0 m in 5 s. What is its average speed in m/s?

4. A spacecraft travels 10 m, 100 m, 500 m, 4,200 m respectively during the first four seconds after launch. What is the average speed at the end of each second?

5. An electron travels 4.82 m in 0.0036 s. What is its average speed?

6. Joella throws out a runner at home plate from shortstop, a distance of 48.3 m, in 1.84 s. With what speed did she throw the ball?

7. A train covers 0.61 m in the first second it is underway, 5.9 m in the second second, 18.2 m in the third second, and 32 m in the fourth second. What is the train’s average speed at the end of each second?

8. Willie swift drives a hockey puck into the goal at a speed of 34.8 m/s. From a distance of 60 m, how long will it take to reach the net?

9. A high speed train between Shin-Obuku and Tokyo averages 78.8 m/s. If the trip takes 58 minutes and 0 s, how far apart are the cities?

10. The Fawzi brothers take their bobsled down a 2 km hill at an average speed of 24 m/s. How long does the trip take?

11. A police officer sees the flash of a gun in the hands of Terrible Tom, the burglar, 125 m away. If the bullet travels at 585 m/s, how much time does she have to dodge the bullet?

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Acceleration

1. A speed boat increases its speed from 42 m/s to 88 m/s in a period of 4 s. What is the boats acceleration during this period?

2. On a runway a jet plane traveling at 58.3 m/s. 8 s later it takes off at 94.4 m/s. During this time what is the planes acceleration?

3. The same plane lands at a speed of 51.4 m/s and comes to a rest 36.2 s later. What is the acceleration during the landing?

4. Bob Ulster time a race car as it passes two points on a track. Its speed at those two points is 43.2 m/s and 68.7 m/s. If the car requires 2 s to travel between these two points, what is the cars acceleration?

5. Felix steals second base running at a speed of 4.2 m/s. He slides into second from a distance of 3.1 m. What is his acceleration during the slide, and what time is required for him to complete the slide?

6. The space shuttle leaves its launch pad with a uniform acceleration of 8.5 m/s2. What will be its speed after 1.0 s? After 10 s? After 40 s?

7. Donna swings at a racquetball moving with a forward speed of 3.0 m/s. She hits the ball with a force that accelerates it by 2.5 m/s2 for 0.8 s. What is the final velocity of the ball?

8. A spacecraft orbits at uniform speed of 1050 m/s. The firing of one of its rockets gives it an acceleration of 185 m/s2. What will be its new speed after 12.5 s of rocket ignition?

9. The driver of a bobsled brakes the speed of his sled from 24.8 m/s to 12.2 m/s. If the brakes are applied for 1.4 s, what was the rate of acceleration?

10. An airplane, traveling 39.5 m/s at the moment it touches the runway, runs off the end of the runway still traveling at 10.2 m/s. If the plane’s rate of acceleration was -1.6 m/s2, how long and how far did the plane travel along the runway?

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Acceleration Due to Gravity

1. A stone dropped from the top of a building, strikes the ground in 4.2 s. How tall is the building?

2. Silas MacEvil pushes a safe off the top of a building 200 m tall. How much time does his victim on the ground below have to move out of the way? At what speed will the safe hit the ground?

3. A paratrooper jumps from an airplane traveling 33.3 m/s at a height of 400 m. If his parachute must open 200 m above the ground, how long does he have for the chute to open?

4. Farsley Henworth hits a pop-foul directly upward in a baseball game. 4.2 s later, the catcher drops the ball. How high was the ball hit into the air?

5. A bomb dropped from an airplane is given an initial downward speed of 10.4 m/s. What is its final velocity if it hits the ground 40.3 s after being released?

6. An empty propane tank dropped from a hot air balloon hits the ground with a speed of 148.3 m/s. From what height was the tank released?

7. A baseball thrown directly upward with an initial speed of 25 m/s will rise to what height? How long does the ball take to reach its highest point? What is its velocity when it hit the ground again?

8. A native sitting 30.0 m up in a tree throws his spear at an armadillo on the ground directly below. He releases the spear at 5.5 m/s. What is the speed with which the spear reaches the ground? How much time does the armadillo have to dodge the spear from the time it is released?

9. A bullet is fired directly upward with a speed of 330 m/s. How far above the ground will the bullet be in 65 s?

10. Josephus hurls a rock downward from a cliff 14.5 m above a lake. One second later, the rock hits the lake. What initial speed did Josephus give the rock?

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Speed and Acceleration

1. A rocket accelerates upward from rest with a uniform acceleration of 4.2 m/s2. How far will the rocket have traveled at the end of 8 s?

2. The brakes on a car permit it to decelerate at the rate of -0.8 m/s2. How much distance is required to stop the car when it is traveling at 16.6 m/s?

3. A solar powered aircraft reaches lift-off speed of 33.3 m/s in 300 m. What is the acceleration of the plane?

4. A motorcycle traveling 30.0 m/s decelerates at the rate of -2.0 m/s2. What distance does it travel before coming to a rest, and how long does it take to stop?

5. Beth and Rosa brake their racing sled so that it decelerates at a uniform rate of 0.43 m/s2. How long does it take to stop if it travels 85 m before coming to a stop?

6. Tests on a new Speedmobile show that it can decelerate from 96.2 m/s to 39.7 m/s in 4.35 s. What distance does the car travel in this time? What is the cars rate of deceleration during this time?

7. Andrew kicks a croquet ball down a hill so that it leaves the top of the hill with a speed of 20 cm/s. It accelerates at a constant 10 cm/s2. How far will the ball travel in 30 s?

8. Donna-Jeanne sees an elephant dart into the road 50 m ahead of her car while she is driving at 18 m/s. She slams on her brakes, which decelerate the car at a rate of -5.8 m/s2. Will she be able to avoid hitting the elephant?

9. The Whizzbang Car Company finds that its new racing car will accelerate ar a uniform rate of 6.39 m/s2 over a 1000 m track. How long will it take the car to cover this distance?

10. A rocket traveling 50 m/s accelerates at a rate of 2.0 m/s2. What is the speed of the rocket after it has traveled 500 m, and what time does it take to reach this speed?

Name_____________________

Universal Gravity

1. What is the F=force of attraction between two metal spheres, each of which has a mass of 2.0 x 104 kg, if the distance between their centers is 4.0 cm?

2. Two students in a physics class sit 80 cm apart. Their masses are 42 kg and 58 kg. By how much are they attracted to each other?

3. The force of gravitational attraction between two lead spheres 2 m apart is 4.832 x 10-3 N. The mass of one sphere is 4500 kg. What is the mass of the other sphere?

4. Calculate the gravitational force of attraction between a proton and a neutron separated by a distance of 1.2 x 10-13 m if the masses of the two particles are 1.673 x -27 kg and 1.675 x 10-27 kg respectively.

5. The gravitational force between the earth and the moon is 1.9 x 1020 N. The masses of the two bodies are 7.36 x 1022 kg and 5.98 x 1024 kg respectively. The distance between them is 3.80 x 108 m. From this information, calculate the value of G, the gravitational constant.

6. An artificial satellite placed in orbit has a mass of 1250 kg. It travels at an average distance of 222.5 km above the earth’s surface. The radius of the earth is 6370 km. What acceleration due to gravity does the earth give the satellite?

7. From the radius (1740 km) and mass (7.35 x 1022 kg) of the moon, determine g for this body.

8. The mass of the sun can be calculated knowing that the diameter of the earth’s orbit is 3.0 x 108 km and the length of the solar year is 365.3 days. The mass of the earth is 5.98 x 1024 kg. What is the solar mass determined this way?

9. With what speed is a 450 kg artificial satellite traveling if it orbits the earth exactly once a day (23 hr 56 min)?

10. The first human to land on the surface of Jupiter weighs 588 N on earth. The mass of the planet is 1.88 x 1027 kg and its radius is 71,800 km. What will be her weight on Jupiter?

Name_____________________

Impulse and Momentum

1. What is the momentum of a 1 kg goose flying through the air with a speed of 1.5 m/s?

2. Ambrose decides that the easiest way to find the weight of a large metal ball is to fire it through space and measure its momentum. He finds that when the ball is moving at a speed of 200 m/s, it has a momentum of 1.6 x 104 kg-m/s. From this, calculate the weight of the ball.

3. A baseball with a mass of .15 kg is thrown by a pitcher with a speed of 45 m/s and hit by a batter. The ball is in contact with the bat for 0.01 s and is driven directly into center field with a speed of 55 m/s. What is the momentum of the thrown ball, the batted ball, and the impulse exerted on the ball?

4. A rifle with a mass of 2.0 kg is used to fire a bullet with a mass of .05 kg. The bullet leaves the gun with a speed of 200 m/s. What is the recoil velocity of the gun?

5. An apple with a mass of 100 g falls on Isaac Newton’s head from a height of 2.0 m. With what momentum does the apple hit Isaac’s head?

6. A Cadillac with a mass of 2500 kg, moving toward the right, collides with a VW with a mass of 1000 kg. After the collision their bumpers lock. Before the impact the Cadillac has a speed of 24 m/s and the VW is standing still. How fast are the two cars traveling after the collision?

7. Suppose that in the previous problem the VW was moving at a speed of 33 m/s, toward the left, and the Cadillac at a speed of 4 m/s, towards the right. They collide head on and once again their bumpers lock. What is the magnitude and direction of the two cars after the impact?

8. The NYPD determines the muzzle velocity of a new pistol by firing a 5.0 kg bullet into a 2 kg wood block. The bullet imbeds into the block and the two move a distance of 82 cm in 1 s. What is the muzzle velocity of the bullet?

9. Two space satellites collide. Satellite #1, mass 248.2 kg, is traveling due east at a velocity of 285 m/s and satellite #2, mass 14.9 kg, is traveling due west at a velocity of 328.2 m/s. The two satellites bounce of one another. Describe the motion of each satellite after the collision.

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Fnet = ma

1. A large ball is struck with a force of 850 N giving it an acceleration of 75.83 m/s2. What is the mass and weight of the ball?

2. Two students pull on a 10 kg box. One student applies a 15 N force, toward the left, and the other student applies a 7 N force, to the right. What is the magnitude and direction of the boxes acceleration?

3. A bus traveling 23.6 m/s is brought to a stop in 135 m. If the mass of the bus is 2250kg, what was the force applied by the brakes to bring it to a stop?

4. A rifle bullet leaves the barrel of a gun at 800 m/s. The barrel is 0.8 m long and the mass of the bullet is .02 kg. What force was required to accelerate the bullet?

5. Amos drags a load of cement blocks with a mass of 50 kg across a wooden floor. The coefficient of kinetic friction between the blocks and the floor is 0.25. If Amos exerts a constant force of 185 N on the load, how fast will it be moving after 10 s?

6. A box with a mass of 50 kg is placed, on a scale, in an elevator. What does the scale read if the elevator is accelerating upward at a rate of 2 m/s2? What does the scale read if it is accelerating downward at the rate of 3 m/s2?

7. The force required to move an 8.24 kg metal cube across an oak floor in measured. The force needed to get the cube moving is found to be 42.8 N, while the force required to keep it moving at constant speed is 32.5 N. From this data, calculate the coefficients of static and kinetic friction between the two materials.

8. A 5 kg block is being accelerated at 6 m/s2 across a rough horizontal surface by a force of 50 N. What is the magnitude of friction force acting on the block?

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