Honor Physics Review

Two identical cars P and Q are travelling along a straight road. Car Q is travelling at twice the speed of car P. The brakes are applied to both cars, producing the same constant deceleration. Which graph shows how the velocity v of each car varies with time?

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On a particular railway, a train driver applies the brake of the train at a yellow signal, a distance of 1.0 km from a red signal, where it stops. The maximum deceleration of the train is 0.2 m/s². Assuming uniform deceleration, what is the maximum safe speed of the train at the yellow signal?

• 20 m/s

• 40 m/s

• 200 m/s

• 400 m/s

A force F is applied to a freely moving object. At one instant of time, the object has velocity v and acceleration a. Which quantities must be in the same direction?

• a and v only

• a and F only

• v and F only

• v, F and a

A thrown stone hits a window, but doesn't break it. Instead it reverses direction and ends up on the ground below the window. In this case, we know:

• the force of the stone on the glass > the force of the glass on the stone.

• the force of the stone on the glass = the force of the glass on the stone.

• the force of the stone on the glass < the force of the glass on the stone.

• the stone didn't slow down as it broke the glass.

A block of mass 4.0 kg rests on a horizontal surface where the coefficient of kinetic friction between the two is 0.20. A string attached to the block is pulled horizontally, resulting in a 3.0 m/s² acceleration by the block. Find the tension in the string. (g = 9.80 m/s²)

• 12 N

• 7.8 N

• 20 N

• 4.2 N

A projectile is launched at an angle above the ground. The horizontal component of the projectile’s velocity, v_x, is initially 40 meters per second. The vertical component of the projectile’s velocity, v_y, is initially 30 meters per second. What are the components of the projectile’s velocity after 2.0 seconds of flight? [Neglect friction.]

• v_x = 40 m/s and v_y = 10 m/s

• v_x = 40 m/s and v_y = 30 m/s

• v_x = 20 m/s and v_y = 10 m/s

• v_x = 20 m/s and v_y = 30 m/s

As shown in the diagram below, a student standing on the roof of a 50-meter-high building kicks a stone at a horizontal speed of 4 meters per second. How much time is required for the stone to reach the level ground below? [Neglect friction.]

• 3.19 s

• 5.10 s

• 10.2 s

• 12.5 s

A mass of 2.0 kg rests on a frictionless surface. It is attached to a 1.0 kg mass by a light, thin string which passes over a frictionless pulley. The 1.0 kg mass is released and it accelerates downwards. What is the speed of the 2.0 kg mass as the 1.0 kg mass hits the floor, having fallen a distance of 0.50 m?

• 1.8 m/s

• 2.2 m/s

• 3.1 m/s

• 9.8 m/s

A cannon fires a cannonball with an initial speed v at an angle α to the horizontal. Which equation is correct for the maximum height H reached?

• H = (v² sin²α) / (2g)

• H = (v² cos²α) / (2g)

• H = (v²) / (2g)

• H = (v² sinα) / (2g)

A 2.0 × 10³ kilogram car travels at a constant speed of 12 meters per second around a circular curve of radius 30 meters. What is the magnitude of the centripetal acceleration of the car as it goes around the curve?

• 0.40 m/s²

• 4.8 m/s²

• 800 m/s²

• 9.600 m/s²