Physics Answers

An aeroplane has a maximum acceleration of 6.0 m s–2. Calculate the minimum length for a straight runway so that the aeroplane, starting from rest, can safely take off at a velocity of 90 m s−1.

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he diagram shows the initial velocity and the final velocity of a ball hit by

a racquet. The ball is in contact with the racquet for a time of 0.25 s.

Calculate: a the change in the velocity of the ball.b the average acceleration of the ball.

velocity against time graph is given for an object. Explain how you would use the graph to determine: a the acceleration of the object at any time. b the total displacement of the object.

a A student writes the following statement in his summary notes: Acceleration is the rate of change of speed. Explain why this statement is wrong.i Explain what is meant by deceleration. ii State the unit for deceleration.

A 4.58 kg pendulum hangs in an elevator. The tension in the string supporting the pendulum if the elevator moves downward with a constant velocity is ab.c N [up]. Input the values of a, b and c into the blank and use the guidelines below:

• Do not include a positive or negative sign.
• Include a decimal in your answer.
• Use a acceleration value of 9.81 m/s²
• Let up be positive

two blocks of masses m1=4.5 kg and m2=6.5 kg resting on a frictionless surface are connected by a light inextensible cord. A horizontal force F of 33N directed to the right is applied to the block with m1 and a horizontal force F of 11N directed to the left is applied to the block with m2. find the acceleration of the system and the tension in the rope.

The orbital speed of the Earth around the Sun is 30 km/s. In one year, how many seconds do the clocks on the Earth lose with respect to the clocks of an inertial reference frame at rest relative to the Sun

A muon formed high in the Earth’s atmosphere is measured by an observer on the Earth’s surface to travel at speed 𝑣 = 0.990𝑐 for a distance of 4.60 km before it decays into an electron, a neutrino, and an antineutrino (𝜇− → 𝑒− + 𝜈 + 𝜈̅).  

(a) For what time interval does the muon live as measured in its reference frame?  

(b) How far does the Earth travel as measured in the frame of the muon? 

A non-flat screen, older style television display (see figure) works by accelerating electrons over a short distance to relativistic speed, and then using electromagnetic fields to control where the electron beam strikes a fluorescent layer at the front of the tube. Suppose the electrons travel at 6.00 × 107 m/s through a distance of 0.200 m from the start of the beam to the screen.  

(a) What is the time of travel of an electron in the rest frame of the television set?  

(b) What is the electron’s time of travel in its own rest frame?

The Hypersonic Technology vehicle 2 (HTV-2) is an experimental rocket vehicle capable of travelling at 21000 km/h (5830 m/s). If an electronic clock in the HTV-2 measures a time interval of exactly 1s duration, what would observers on Earth measure the time interval to be?