Physics I-H UAM Motion Daily Grade: Due ______Show All Your Work Neatly on Your Own Paper
Physics I-H UAM motion Daily Grade: Due ______Show all your work neatly on your own paper !!!!
- A sled starting from rest slides down a hill with uniform acceleration and travels 9.0 m in 3.0 s.
- What is the average velocity for the 3.0 s?
- What is its velocity at the end of the 3.0 s (at t = 3.0s)?
- What is the acceleration of the sled?
- How long will it take to reach a velocity of 24 m/s?
- A supersonic jet flying at 145 m/s is accelerated uniformly at the rate of 23.1 m/s2 for 20.0 s. What is its final velocity? The speed of sound in air is 331 m/s. How many times the speed of sound is the plane’s final velocity?
- Superman slams head-on into a locomotive speeding along at 60 km/h, bringing it smoothly to rest in anamazing .001 s and saving Lois Lane, who was tied to the tracks. Calculate the average deceleration of the train in m/s2.
- If a bullet leaves the muzzle of a rifle with a speed of 600 m/s, and the barrel of the rifle is 0.9 m long, what is the acceleration of the bullet while in the barrel? If the gravitational acceleration on Earth is 10 m/s2, how does the acceleration of the bullet compare to the acceleration of an object toward the Earth?
- Estimate how fast Colton’s air bag must inflate to effectively protect him in a head-on collision at 100 km/h .
Assume the impact occurs over a distance of about 1.0 m and deceleration is uniform. (ans: 0.07s)
- Highway safety engineers build soft barriers so that when Shyam runs into them he will decelerate at a safe rate. When he wears his seat belt he can withstand an acceleration of -300 m/s2. How thick should the barriers be to safely stop Shyam when he hits the barrier at 110 km/h? (ans: 1.6 m)
- Mr. Lathan, doing 40.0 mph in a 25 mph zone, approaches a parked police car. The instant he passes the police car, the police begin their pursuit. If Mr. Lathan maintains a constant velocity, and the police car accelerates with a constant acceleration of 4.50 m/s2, (a) how long does it take for the police car to catch Mr. Lathan? (ans: 8.1s) (b) how far have the two cars traveled in this time (ans: 147m), and (c) what is the velocity of the police car when it catches him?
(ans: 36.5m/s)
Part II: and gravity
1. As a freely falling object speeds up, what is happening to its acceleration due to gravity? Does it increase, decrease, or remain the same?
2. How long does it take a brick to reach the ground if dropped from a height of 65 m? What will be its velocity just before it reaches the ground? (3.6s; 35.3 m/s )
3. The tallest Sequoia sempervirens tree in California’s RedwoodNational Park is 111 m tall. Suppose an object is thrown downward from the top of that tree with a certain initial velocity. If the object reaches the ground in 3.80 s, what is the object’s initial velocity? (-10.6 m/s Why negative?)
4. A rock is thrown vertically upward with a speed of 10 m/s from the edge of a cliff which is 65 m high.
a. What will be its speed just before hitting? (-37 m/s)
b. How much time will it take to reach the bottom of the cliff? (4.7 s)
5. In a scientific test conducted in Arizona, a special cannon called HARP (High Altitude Research Project) shot a projectile straight up to an altitude of 180.0 km. If the projectile’s initial speed was 3.00 km/s, how long did it take the projectile to reach its maximum height? (120 s)
6. Kyle is flying a helicopter when he drops a bag. When the bag has fallen 2.0s, what is the bag's velocity and how far has the bag fallen? Use -10 m/s2 for g. ( -20 m/s; -20m)
Kyle is flying the same helicopter and it is rising at 5.0 m/s when he releases the bag. After 2.0 s what is the bag's velocity, how far has the bag fallen and how far below the helicopter is the bag? (-15 m/s; -10m; 20m)
Kyle's helicopter now descends at 5.0 m/s as he releases the bag. After 2.0 s what is the bag's velocity, how far has the bag fallen and how far below the helicopter is the bag? ( -25 m/s; -30m; 20m)
Challenging !!!!
A common flea is recorded to have jumped as high as 21 cm. Assuming that the jump is entirely in the vertical direction and that air resistance is insignificant, calculate the time it takes the flea to reach a height of 7.0 cm. (0.04 s)
Some cockroaches can run as fast as 1.5 m/s. Suppose that two cockroaches are separated by a distance of 60.0 cm and that they begin to run toward each other at the same moment. Both insects have constant accelerationuntil they meet. The first cockroach has an acceleration of 0.20 m/s2 in one direction, and the second one has an acceleration of 0.12 m/s2 in the opposite direction. How much time passes before the two insects bump into each other? (1.9 s)
Mr. Lathan, doing 40.0 mph in a 25 mph zone, approaches a parked police car. The instant he passes the police car, the police begin their pursuit. If Mr. Lathan maintains a constant velocity, and the police car accelerates with a constant acceleration of 4.50 m/s2, (a) how long does it take for the police car to catch Mr. Lathan? (8.1 s)
(b) how far have the two cars traveled in this time (147m), and (c) what is the velocity of the police car when it catches him? ( 36.5 m/s)