Mechanics | Relativity Answers

A student is given a spring balance that has a scale in newtons. The student is told that the acceleration of free-fall is 10 m/s2. (i) Describe how the student could find the mass of an irregular solid object.

Describe how the student could go on to find the density of the object.

A defibrillator passes a brief burst of current through the heart to restore normal beating. In one such defibrillator, a 50.0x10-6 F capacitor is charged to 6.00x103 V. Paddles are used to make an electrical connection to the patient's chest. The electrical resistance of the patient (from paddle to paddle) is 245 Ω. A pulse of current lasting 1.50x10-3 s partially discharges the capacitor, i.e., the switch is closed for 1.50x10-3 s and then opened.

What is the time constant of this circuit?
What is the energy initially stored in the capacitor?
What is the maximum charge on the capacitor before it is discharged?
How much energy is dissipated in the patient (resistor) during the 1.50x10-3 s that the switch is closed?

A square conducting loop of side L contains a resistor, R. It is placed in a magnetic field, B, directed into the page and which changes as a function of time t according to the relationship B = at + b, where a and b are positive constants. No magnetic field exists outside the loop.

Derive an expression for the induced current in the loop in terms of a, b, L, and/or R (note: not all terms may be in your final expression).
Derive a similar expression in terms of a, b, L, and/or R for the power dissipated in the resistor.
Does the induced current flow clockwise or anticlockwise? Explain.
The square loop is replaced by a circular copper loop of diameter 0.20 m and consisting of 50 turns. If a = 10 and b = 2, determine the emf induced in the circular loop.

What mass should be hung on an elastic material of stiffness 100N/m to produce an extension of 20cm.

A ball of 1.2kg with velocity 4ms-1 hit by a car which moving in same direction with the ball. the velocity of the ball increase to 10ms-1 in 0.5s. what is the impulse on the ball?

Data:
length of pendulum =l=0.5m
acceleration =g=9.8m/s²
To find:
frequency =?

. A 9,100 kg tractor is moving (horizontally) at 5.0 km h−1 when the 80 kg driver has
to brake suddenly to come to a stop before hitting a tree stump. If the tractor and
driver come to rest over a horizontal distance of 2.0 m, and the acceleration of the
tractor and driver is constant, what is the magnitude of the net force on the driver

. A 25mm diameter rod is subjected to an axial load of 20 000N. If the material is elastic with a Young's Modulus of Elasticity E = 70,000Nmm-2 estimate the percentage elongation.

A mass of 1019Kg is supported by two wires A and B each made of a different material. Before loading the wires are of equal length. After loading they are still of equal length. Find the load carried by each wire.
(WA = 3066N) (WB = 6930N)
Wire
Diameter mm
E Nmm-2
A

1

206,000
B
2

116,000