Q: A projectile is launched at an angle $$\theta$$ with initial speed $$v_0. $$What is the maximum height reached by the projectile?

$$\frac{v_0$^2 \sin^2$ \theta}{2g}$$

Question 1

A flea rapidly extends its legs, reaching a takeoff speed of $$1\ \mathrm{m/s}$$ over a distance of $$0.50\ \mathrm{mm}. $$What is the flea’s acceleration as it extends its legs, and how long does it take the flea to leave the ground after it begins pushing?

Accepted Answer

$$a = 1000\ \mathrm{m/s^2$};\ t = 0.001\ \mathrm{s}$$

Question 2

In a movie, a villain is rescued from the ocean by grabbing a ladder hanging from a helicopter. He lets go of his briefcase of counterfeit money when he is $$130\ \mathrm{m}$$ above the water. If the briefcase hits the water $$6.0\ \mathrm{s}$$ later, what was the speed at which the helicopter was ascending?

Accepted Answer

$$7.73\ \mathrm{m/s}$$

Question 3

A driver has a reaction time of $$0.50\ \mathrm{s}$$, and the maximum acceleration for braking is $$6.0\ \mathrm{m/s^2$}. $$She is driving at $$20\ \mathrm{m/s}$$ when she sees an obstacle $$50\ \mathrm{m} in $$front of her. Can she stop the car in time to avoid a collision?

Accepted Answer

Yes, she will stop with $$6.7\ \mathrm{m} to $$spare.

Question 4

A ball is thrown horizontally from a $$20\ \mathrm{m}-$$high building with a speed of $$5\ \mathrm{m/s}. $$How far from the base of the building does the ball hit the ground?

Accepted Answer

$$10\ \mathrm{m}$$

Question 5

An archerfish shoots a stream of water at an insect $$26\ \mathrm{cm}$$ away, aiming at an angle of $$39^\circ$$ above the waterline. The stream leaves the fish’s mouth at $$3.7\ \mathrm{m/s}. $$Will the stream hit an insect sitting $$17\ \mathrm{cm}$$ above the waterline?

Accepted Answer

The stream hits the insect, lunch time for Fishy!

Question 6

A person walks off a $$15.0\ \mathrm{m}$$ cliff with a horizontal speed of $$3.00\ \mathrm{m/s}$$, but there is a strong wind blowing horizontally towards the cliff, causing an acceleration toward the cliff of $$3.50\ \mathrm{m/s^2$}. $$How much time would it take for them to reach the water at the bottom? What is their horizontal displacement at that time?

Accepted Answer

$$t = 1.75\ \mathrm{s};\ \Delta x = 12\ \mathrm{m}$$

Question 7

A car has a maximum acceleration of $$4.0\ \mathrm{m/s^2$}$$ when it has a total mass of $$1200\ \mathrm{kg}. $$What is its maximum acceleration after picking up four passengers and their luggage, adding an additional $$400\ \mathrm{kg} of $$mass?

Accepted Answer

$$3.0\ \mathrm{m/s^2$}$$

Question 8

During a baseball game, a player hits a stationary ball of mass $$0.14\ \mathrm{kg} so $$that it leaves the bat at $$12\ \mathrm{m/s}$$ after being in contact with the bat for $$2.0\ \mathrm{ms}. $$What is the net force on the ball during the hit?

Accepted Answer

$$840\ \mathrm{N}$$

Question 9

In the sport of curling, an $$80\ \mathrm{kg}$$ player releases a $$20\ \mathrm{kg}$$ stone that travels $$27.9\ \mathrm{m}$$ before coming to rest. The friction force acting on the stone is $$2.0\ \mathrm{N}. $$What was the speed of the stone when the player released it?

Accepted Answer

$$2.36\ \mathrm{m/s}$$

Question 10

A graph shows the acceleration of a train as a function of time. The train moves to the right with a positive velocity and slows down to a stop at $$t=2\ \mathrm{s}$$, then remains at rest. Which of the following best describes the acceleration graph for $$0 \u003c t \u003c 4\ \mathrm{s}$$?

Accepted Answer

Negative constant acceleration for $$0 \u003c t \u003c 2\ \mathrm{s}$$, then zero acceleration for $$2 \u003c t \u003c 4\ \mathrm{s}.$$

Question 11

If an object is pulled by a force and its acceleration is measured, which of the following statements is correct according to Newton’s Second Law?

Accepted Answer

The acceleration is directly proportional to the force and inversely proportional to the mass: $$a = \frac{F}{m}.$$

Question 12

A projectile is launched horizontally from a height $$h$$ with initial speed $$v_0. $$Neglecting air resistance, which equation gives the time it takes to hit the ground?

Accepted Answer

$$t = \sqrt{\frac{2h}{g}}$$

Question 13

A $$0.20\ \mathrm{kg}$$ object is pulled by a force of $$2\ \mathrm{N}$$ and accelerates at $$10\ \mathrm{m/s^2$}. If $$another object is pulled by the same force and accelerates at $$5\ \mathrm{m/s^2$}$$, what is its mass?

Accepted Answer

$$0.40\ \mathrm{kg}$$

Question 14

A cyclist accelerates from rest at a constant rate. If the acceleration is $$2\ \mathrm{m/s^2$}$$, how far does the cyclist travel in $$4\ \mathrm{s}$$?

Accepted Answer

$$8\ \mathrm{m}$$

Question 15

A ball is thrown horizontally from a cliff and lands $$30\ \mathrm{m}$$ from the base after $$2.5\ \mathrm{s}. $$What was its initial horizontal velocity?

Accepted Answer

$$12\ \mathrm{m/s}$$

Question 16

A $$0.5\ \mathrm{kg}$$ object is acted on by a net force of $$3\ \mathrm{N}$$ for $$4\ \mathrm{s}. $$What is its final velocity if it starts from rest?

Accepted Answer

$$12\ \mathrm{m/s}$$

Question 17

A car traveling at $$25\ \mathrm{m/s}$$ comes to a stop in $$5.0\ \mathrm{s}$$ with constant acceleration. What is the magnitude of its acceleration?

Accepted Answer

$$5.0\ \mathrm{m/s^2$}$$

Question 18

A projectile is launched at an angle $$	heta$$ with initial speed $$v_0. $$What is the maximum height reached by the projectile?

Accepted Answer

$$\frac{v_0$^2 \sin^2$ 	heta}{2g}$$

Physics Exam 1 Jeopardy: Kinematics and Newton's Second Law

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