Physics Answers

Using Snell’s law, determine the constant when the angle of incidence and the angle of refraction are:

a) 50˚ and 30˚

b) 30˚ and 18˚

c) 60˚ and 38˚

A ball is projected vertically upwards with an initial velocity of

30m/s. Neglecting air resistance and taking g to be 10m/s2.

a. Find its maximum height

(2)

b. The time taken to return to its starting point.

(3)

c. Plot a velocity-time graph for its downward motion

(4)

d. Predict what would happen to the time of flight if

Use dimensional analysis to show the correct dimensions

for quantities below.

(8)

QUANTITY. DIMENSION

FORCE

POWER

PRESSURE

WORK, ENERGY

b. Prove that the equation F=ma is dimensionally correct

A stone is thrown at an initial speed of 125 ft/s directed 60 ° above the horizontal at the cliff of

height, y. The stone strikes the cliff 5.8 seconds after launching. Find the height of the cliff and

the speed of the stone just before impact at the top of the cliff.

What is the resultant of a displacement 6.0 miles North and one 9.0 miles East?

1. An underwater swimmer looks up toward the surface of the water on a line of sight that makes an angle of 25˚ with a normal to the surface of the water. What is the angle of incidence in air for the light rays that enter the swimmer’s eye?

2. In each of the following questions, the second medium is air.

a) What is the critical angle if the index of refraction for a medium is 1.68?

b) What is the index of refraction of a medium if the critical angle is 40˚?

1. Light travels from air into water. If the angle of refraction is 30˚, what is the angle of incidence?

2. A ray of light in air strikes a block of quartz at an angle of incidence of 30˚. The angle of refraction is 20˚. What is the index of refraction in quartz? 

1. Using Snell’s law, determine the constant when the angle of incidence and the angle of refraction are: a) 50˚ and 30˚ b) 30˚ and 18˚ c) 60˚ and 38˚

2. a) What is the angle of refraction in a medium if the angle of incidence in air is 48˚ and the index of refraction of the medium is 1.58? b) What is the angle of incidence in a medium in the case where the angle of refraction in air is 40˚ and the index of refraction of the medium is 1.58?

3. A ray of light passes from air into water at an angle of incidence of 50˚. What is the angle of refraction? (HINT: You will need to use the sin1 function on your calculator).

A skier traveling 11.0 m/s reaches the foot of a steady upward 19° incline and

glides 15 m up along this slope before coming to rest. What was the average

coefficient of friction? (use conservation of energy method or work energy

theorem)

In a common test for cardiac function (the “stress test”), the patient walks on an

inclined treadmill. Estimate the power required from a 75-kg patient when the

treadmill is sloping at an angle of 12° and the velocity is 3.1 km/h.