Physics Answers

The wave length of a travelling wave is 5m at a frequency of 12Hz and has an amplitude of 15m, write down the equation of wave

What is the amount of heat required to change 2kg of ice at -15°c to water at 70°c ( C=4200jkg-¹k-¹

A. An airliner must reach a speed of 110 m/s to take off. If the available runway is 2.4 km

and the aircraft accelerates uniformly from rest at one end, what minimum acceleration

must be available if it is to take off?

B. A speeding motorist driving a car, passes a traffic police officer on a stationary

motorcycle. The police officer immediately gives chase: his uniform acceleration is

4ms-2

, and by the time he draws level with the speeding car, the police officer is

travelling at 30ms-1

.

i. How long did it take for the police officer to catch the car?

ii. If the speeding motorist continued to travel at a steady speed during the

chase, what was his speed?

C. A stone is thrown vertically upwards with a speed of 24.0 ms-1

. Using g = 9.8 ms-2

and

ignoring air resistance:

i. How much time is required to reach this height?

ii. Why are there two answers to (ii.)?

iii. Sketch the velocity-time graph for the stone, from it is released until it

returns to the thrower.

1.) Find the angular velocity of an object in non-circular motion with 2-m radius circular path. Its tangential speed is 10 m/s.

a. 5 radians per second

b. 50 radians per second

c. 20 radians per second

d. 10 radians per second

2.) In non-uniform circular motion, the direction of the centripetal acceleration is _____ inwards.

a. sometimes

b. oftentimes

c. always

d. never

3.) In uniform circular motion, angular velocity is

a. varying

b. constant, nonzero

c. increasing

4.) A satellite is placed in a circular orbit to observe the surface of Mars from an altitude of 144 km. The equatorial radius of Mars is 3397 km. If the speed of the satellite is 3480 m/s, what is the magnitude of the centripetal acceleration in m/s²of the satellite?

a. 3.42

b. 2.17

c. 2.99

d. 4.05

A train of mass 200kN has a frictional resistance of 5N per kN. The speed of the

train, at the top of an inclined of 1 in 80 is 45 km/h. Find the speed of the train after

running down the incline for 1km.

A. An object of mass m is placed on an inclined plane with a rough surface. Derive an

equation of the acceleration of the object sliding down the incline. [Be sure to

include an appropriate diagram highlighting the relevant forces] (10 marks)

B. A train of mass 200kN has a frictional resistance of 5N per kN. The speed of the

train, at the top of an inclined of 1 in 80 is 45 km/h. Find the speed of the train after

running down the incline for 1km. (10 marks)

A student builds and calibrates an accelerometer, which she uses to determine the speed of her

car around a certain unbanked highway curve. The accelerometer is a

plumb bob with a protractor that she attaches to the roof of her car. A friend riding in the car

with her observes that the plumb bob hangs at an angle of 15.0° from the vertical

when the car has a speed of 23.0 m/s.

A. What is the radius of the curve? (8 marks)

B. What is the centripetal acceleration of the car rounding the curve? (7 marks)

C. What is the speed of the car if the plumb bob deflection is 9.00° while

rounding the same curve? (5 marks)

A body of mass 25kg falls on the ground from a height of 19.6m. The body penetrates into the

ground. Assume the resistance by the ground to penetrate is constant and equal to 4998N.

Take g = 9.8m/s2

.

A. Find the final velocity of the body just before it hits the ground. (8 marks)

B. Calculate the retardation (acceleration) when the body is penetrating the ground.

(7 marks)

C. Find the distance through which the body will penetrate into the ground.

(5 marks)

An object of mass m is placed on an inclined plane with a rough surface. Derive an equation of the acceleration of the object sliding down the incline. [Be sure to include an appropriate diagram highlighting the relevant forces] 

An airliner must reach a speed of 110 m/s to take off. If the available runway is 2.4 km and the aircraft accelerates uniformly from rest at one end, what minimum acceleration must be available if it is to take off?